Also:

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?
• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

In T372702#10075958, @Tgr wrote:

Also:

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?
• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

I've experienced it on both English Wikipedia & Commons. I did check the "Keep logged in" checkbox.

Thanks @Vestrian24Bio! Do you remember / can check the answers to the other questions by any chance?

Total number of session channel log events:	Top-level autologins:	Autologin errors:

The older error spike is caused by some crawler so I dismissed the more recent one as more of the same but maybe that was wrong. Unlike the older spike, it's accompanied by an increase in top-level autologins (which I'd expect to happen if people have session troubles). OTOH the errors are mainly "not central wiki" which doesn't make a lot of sense - maybe the crawler just switched from normal autologin URLs to top-level autologin URLs for whatever reason? Will have to check the webrequest logs.

In T372702#10076998, @Tgr wrote:

Thanks @Vestrian24Bio! Do you remember / can check the answers to the other questions by any chance?

It happens like once a week, the next time it happens I will make sure to collect the details about cookies. I am using Microsoft Edge Version 128.0.2739.33 (Official build) stable app, beta channel (64-bit) on a Windows 10 Pro Beta Version 22H2 build 10.0.19045.4717 (64-bit) device.

In T372702#10077189, @Tgr wrote:

maybe the crawler just switched from normal autologin URLs to top-level autologin URLs for whatever reason?

Apparently yes. A lot of those requests are from Tencent Cloud IPs, like the previous spike. So this is probably unrelated, and we are back to no visible changes in stats. This also seems to be true per wiki, e.g. successful logins on Wikidata:

Same issue here on the Dutch Wikipedia: 30 minutes ago I was logged out for no apparent reason. My IP is from Odido (previously T-Mobile), so no Tencent.

Edit: forgot to add:

Browser: Firefox
OS: Deepin Linux 23 (based on Debian Bookworm)

@Mondo it seems after getting logged out, you logged in twice in quick succession (two minutes apart), do you remember why that was necessary? Did you get logged out on two different devices at the same time?

@Tgr You're right. I also forgot to add that I checked another browser to see if I was logged out there as well and it turns out I was. That's why I logged in twice.

I just got suddenly logged out again, but this time on Wikidata.

And now I got logged out on my laptop (ChromeOS Flex) and phone (iPhone 15 with iOS 17 and Safari) as well.

Same here on English Wiktionary (iPhone 15 and MacOS)

Just discovered something about this. On Wikimedia Commons, I was in desktop mode, and everything looks fine. Then I visited to Wikipedia (bnwiki), showing logout here. Then visited Commons again, still logged in until I changed it to mobile view. Commons and Meta shows logged in on the desktop view, logged out on the mobile view, while the rest of other wikis shows fully (mobile/desktop) logged out.

In T372702#10103189, @tanbiruzzaman wrote:

Just discovered something about this. On Wikimedia Commons, I was in desktop mode, and everything looks fine. Then I visited to Wikipedia (bnwiki), showing logout here. Then visited Commons again, still logged in until I changed it to mobile view. Commons and Meta shows logged in on the desktop view, logged out on the mobile view, while the rest of other wikis shows fully (mobile/desktop) logged out.

This is expected behaviour lately, as browsers elevated their privacy policies. Clicking the log in button wouldn't require you to enter your credentials again. See also T348388.

In T372702#10103201, @Sjoerddebruin wrote:

In T372702#10103189, @tanbiruzzaman wrote:

Just discovered something about this. On Wikimedia Commons, I was in desktop mode, and everything looks fine. Then I visited to Wikipedia (bnwiki), showing logout here. Then visited Commons again, still logged in until I changed it to mobile view. Commons and Meta shows logged in on the desktop view, logged out on the mobile view, while the rest of other wikis shows fully (mobile/desktop) logged out.

This is expected behaviour lately, as browsers elevated their privacy policies. Clicking the log in button wouldn't require you to enter your credentials again. See also T348388.

Actually that's what I thought at first too, and tried it, but it used to work some times ago, now it doesn't.

In my case, I have been logging out once every 2 days. This is happening only on mobile. I use the latest Chrome browser on Android and the Brave browser on my laptop.

Today I have been logging out 3 times in 2 hours on mobile and 1 time on laptop. It happens to me within 2 weeks with an interval of 2-4 days.

• How frequently is it happening? (One hypothesis would be that login expires after 24 hours, which is the length data is retained in the central session store. Does that sound about right?)

Definitely longer than 24 hours. Maybe ~2-4 days since the last occurrence.

• Is it correlated to some action you are taking, especially visiting another wiki which you have not visited for a while?

I switched to a tab that already had metawiki Special:Watchlist open from the night (local time) before. I had edited on metawiki at 2024-09-01T16:41.

• Which of these cookies does your browser have? centralauth_Session, centralauth_Token, <wiki name>Session, <wiki name>Token (do NOT share the values of the cookies!) When will they expire? Extra useful if you can check right when you get logged out. (You can check in your browser's developer toolbar, e.g. on Chrome it's F12 and then select the Application tab, and the Cookies menu item on the left.)

centralauth_Session: not present, centralauth_Token: not present, <wiki name>Session: present, <wiki name>Token: not present
<wiki name>Token is not present even on wikis where I am logged in.
These are the expiries of all of the CA / wiki cookies present following the logout. CentralAuthAnonTopLevel: 2024-09-02T17:40:32.417Z, centralauth_ss0-Token: 2025-01-15T15:22:42.954Z, centralauth_ss0-User: 2025-01-15T15:22:42.954Z, metawikiSession: Session, metawikiUserName: 2024-09-30T17:36:23.431Z, metawikimwuser-sessionId: Session, metawikiss0-UserID: 2025-01-15T15:22:42.954Z, metawikiss0-UserName: 2025-01-15T15:22:42.954Z

• Are you logged out on all wikis at the same time? If you use other devices (e.g. a mobile phone), are you logged out on those at the same time as well?

I was only logged out of metawiki. I do not use any other device.

• If you experience getting logged out again, the time range when it happened (the time when you opened a page and were logged out, and the last time before that when you opened a page and were still logged in, as accurately as you can remember).

Logged out approximately 2024-09-01T17:40. I had edited on metawiki at 2024-09-01T16:41.

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?

The last wiki that I logged into was loginwiki due to a similar case of this issue last week that I did not note the details for.

• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

Yes

Hi,

I’m Reader of Information. I was typing on Safari when out of no where my account suddenly logged out and published an edit reply under my ip address for a review of deletion.

Reproduce steps (can’t remember all of them but I’ll give what I remember)

1. Click on the thing to log you in when tryna reply logged out
2. Log in on ur mobile device to your account.
3. Go backward to page history to get back to the forum page
4. Type something under a forum as a reply but do not send.

5.Then go to back to the login screen using forward and relogin while logged in

6. It should occur when you press reply.

I don’t know if this will exactly make the bug occur aa it happened a few days ago.

——
Going to reply to anything I see with my experience so I’m going to read the thread to reply to anything.

How frequently is it happening? (One hypothesis would be that login expires after 24 hours, which is the length data is retained in the central session store. Does that sound about right?) It is inconsistent for me. Sometimes its multiple times a day, other times 24 hours.
This has been happening for the last week btw.

Is it correlated to some action you are taking, especially visiting another wiki which you have not visited for a while?

I don’t visit any other wiki other than English Wikipedia.

Which of these cookies does your browser have?
centralauth_Session, centralauth_Token, <wiki name>Session, <wiki name>Token (do NOT share the values of the cookies!) When will they expire? Extra useful if you can check right when you get logged out. (You can check in your browser's developer toolbar, e.g. on Chrome it's F12 and then select the Application tab, and the Cookies menu item on the left.)

It occurs on mobile first before occurring on Desktop so I couldn’t access it.

Are you logged out on all wikis at the same time? If you use other devices (e.g. a mobile phone), are you logged out on those at the same time as well?

I use desktop and wikipedia. It varies. Sometimes at the same time. Other times a few mins apart.

If you experience getting logged out again, the time range when it happened (the time when you opened a page and were logged out, and the last time before that when you opened a page and were still logged in, as accurately as you can remember).

A few hours to 24 hours.

——
Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?

Same wiki

Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

I was curious about this and it seems unchecked is more consistent and last for 24 hours. Checked lasts a shorter amount of time.

I’ve also had an issue where I had to login twice on mobile because it did not register the first login whereas with the desktop I just need to do it once.

A few additional hopefully helpful information:

It seems to be a browser-only issue. The checked works for the app.

I use a password manager when I log in for mobile. When using the password manager on mobile during the login screen I have to log in twice otherwise it doesn't register the information despite saying it does.

I don’t use a password manager on my desktop which ends up making me only log in once. Strange.

Just got logged out again. I'm only getting logged out on my laptop, my phone browser (in desktop mode) remains logged-in the whole time. I wasn't able to capture the first request for enwiki, but I did get the first request for Commons at Wed, 04 Sep 2024 11:50:16 GMT ("wgRequestId":"3453a5cc-b50b-4e6d-a58d-e437b8d2267a"). This was just refreshing a page I had opened last night, where I was previously logged in. [***] are redactions.

{
	"Response Cookies": {
		"centralauth_Session": {
			"expires": "1970-01-01T00:00:01.000Z",
			"httpOnly": true,
			"path": "/",
			"samesite": "None",
			"secure": true,
			"value": "deleted"
		},
		"centralauth_User": {
			"expires": "1970-01-01T00:00:01.000Z",
			"httpOnly": true,
			"path": "/",
			"samesite": "None",
			"secure": true,
			"value": "deleted"
		},
		"commonswikiSession": {
			"expires": "1970-01-01T00:00:01.000Z",
			"httpOnly": true,
			"path": "/",
			"samesite": "None",
			"secure": true,
			"value": "deleted"
		},
		"commonswikiUserID": {
			"expires": "1970-01-01T00:00:01.000Z",
			"httpOnly": true,
			"path": "/",
			"samesite": "None",
			"secure": true,
			"value": "deleted"
		},
		"NetworkProbeLimit": {
			"path": "/",
			"samesite": "Lax",
			"secure": true,
			"value": "0.001"
		}
	}
},
{
	"Request Cookies": {
		"centralauth_Session": "[***]",
		"centralauth_ss0-Token": "[***]",
		"centralauth_ss0-User": "AntiCompositeNumber",
		"centralauth_User": "AntiCompositeNumber",
		"commonswikimwuser-sessionId": "[***]",
		"commonswikiSession": "[***]",
		"commonswikiss0-UserID": "4128838",
		"commonswikiss0-UserName": "AntiCompositeNumber",
		"commonswikiUserID": "4128838",
		"commonswikiUserName": "AntiCompositeNumber",
		"GeoIP": "[***]",
		"NetworkProbeLimit": "0.001",
		"ss0-centralauth_Session": "[***]",
		"ss0-commonswikiSession": "[***]",
		"WMF-Last-Access": "04-Sep-2024",
		"WMF-Last-Access-Global": "02-Sep-2024"
	}
}

From the storage tab for Commons, with devtools opened before the request but checked after the request:

The cross-site request to loginwiki also has all the cookies:

{
	"Request Cookies": {
		"centralauth_ss0-Token": "[***]",
		"centralauth_ss0-User": "AntiCompositeNumber",
		"GeoIP": "[***]",
		"loginnotify_prevlogins": "[***]",
		"loginwikimwuser-sessionId": "[***]",
		"loginwikiss0-UserID": "807180",
		"loginwikiss0-UserName": "AntiCompositeNumber",
		"loginwikiUserName": "AntiCompositeNumber",
		"ss0-centralauth_Session": "[***]",
		"ss0-loginwikiSession": "[***]",
		"WMF-Last-Access": "04-Sep-2024",
		"WMF-Last-Access-Global": "02-Sep-2024"
	}
}

It got the /* Not centrally logged in */ response.
Logouts are happening across all domains, regardless of login domain. It happens on the first request when I turn my computer on, usually 8-10 hours since the last request from that device. It's not every 24 hours, it's been every couple of days. I am using the stay logged in checkbox. Firefox 105.0 on Linux.

One hypothesis is that this issue is related to the increased load on Kask (our login session storage service), see T373826. That has been mostly fixed about an hour ago, and so it's possible but not at all certain that this issue is fixed as well. If you were previously experiencing it regularly, please make a note of whether it keeps happening or not over the next couple of days.

Happened again today, I was logged out from all WMF sites and Central Login didn't work; had to enter the password again and login...

In T372702#10071526, @Nikki wrote:

I have centralauth_Token cookies on both computers where it's happened, both have expiry times in August next year.

It happens while the browser is still running for me. When it happened yesterday, I was editing Wikidata and when I tried to save my edits, it gave me an error saying that it had failed because I was no longer logged in.

It just happened again on me on one of the computers I mentioned here.

In T372702#10075955, @Tgr wrote:

Some details that would be helpful if you are experiencing this:

• How frequently is it happening? (One hypothesis would be that login expires after 24 hours, which is the length data is retained in the central session store. Does that sound about right?)

I stayed logged in since my last comment where I had to log in on the 17th/18th of August.

• Is it correlated to some action you are taking, especially visiting another wiki which you have not visited for a while?

Not as far as I can tell.

• Which of these cookies does your browser have? centralauth_Session, centralauth_Token, <wiki name>Session, <wiki name>Token (do NOT share the values of the cookies!) When will they expire? Extra useful if you can check right when you get logged out. (You can check in your browser's developer toolbar, e.g. on Chrome it's F12 and then select the Application tab, and the Cookies menu item on the left.)

After being logged out, I only had a wikidatawikiSession cookie, which said it was a session cookie.

After logging back in, I have centralauth_Session, centralauth_Token, wikidatawikiSession and metawikiSession. centralauth_Token is set to expire in a year, the others are session cookies.

• Are you logged out on all wikis at the same time? If you use other devices (e.g. a mobile phone), are you logged out on those at the same time as well?

As far as I can tell, I was logged out on all wikis (I checked Wikidata, Meta, Commons and pa.wikipedia.org).

Last time it happened, I stayed logged in on the other computer. I haven't checked yet this time.

• If you experience getting logged out again, the time range when it happened (the time when you opened a page and were logged out, and the last time before that when you opened a page and were still logged in, as accurately as you can remember).

I was still logged in yesterday. I was logged out when I loaded a page today.

According to the browser history, the last Wikidata page I loaded yesterday was at 13:10. After that, I also looked at a few pages on pa.wikipedia.org (a wiki I don't often visit), the last request being at 15:57, and on Commons (a wiki I do often visit), the last being 15:59. My first request today was a Wikidata page at 10:33. (times are UTC+2)

I was definitely still logged when I visited pa.wikipedia.org, because I still had the tab open and could see that I was still logged in when I loaded the page. I don't know whether I was still logged in on Commons.

In T372702#10075958, @Tgr wrote:

Also:

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?

Yes. I almost always log in on Wikidata, and Wikidata is where I notice that I've been logged out.

• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

I can't be 100% sure that I ticked that box, but I assume I must have done, because I wrote in my previous message that the cookies are set to expire next year, and I did not load any Wikimedia pages on this computer at all on the 22nd or 29th of August and still stayed logged in.

(For future reference: I did tick that box this time)

Today I got logged out again on my phone. iPhone 15, iOS 17.6.1, Safari, Dutch Wikipedia (didn't check other languages). Keep me logged in was checked (I always do that, no matter the device).

This morning I was logged out on Meta (but not enwiki) on my phone and logged out on all wikis on my laptop.

• How frequently is it happening? (One hypothesis would be that login expires after 24 hours, which is the length data is retained in the central session store. Does that sound about right?)

~9 days since previous: T372702#10109010

• Is it correlated to some action you are taking, especially visiting another wiki which you have not visited for a while?

I had edited on enwiki at 2024-09-09T07:05Z and metawiki at 2024-09-09T00:15Z.

• Which of these cookies does your browser have? centralauth_Session, centralauth_Token, <wiki name>Session, <wiki name>Token (do NOT share the values of the cookies!) When will they expire? Extra useful if you can check right when you get logged out. (You can check in your browser's developer toolbar, e.g. on Chrome it's F12 and then select the Application tab, and the Cookies menu item on the left.)

centralauth_Session: not present, centralauth_Token: not present, <wiki name>Session: not present, <wiki name>Token: not present
These are the expiries of all of the CA / wiki cookies present following the logout. centralauth_ss0-Token: 2025-01-14T17:35:21.480Z, centralauth_ss0-User: 2025-01-14T17:35:21.480Z, enwikiUserName: 2024-10-09T18:38:06.353Z, enwikimwuser-sessionId: Session, enwikiss0-UserID: 2025-01-13T09:30:09.266Z, enwikiss0-UserName: 2025-01-13T09:30:09.266Z, loginwikiUserName: 2024-10-09T19:03:27.188Z, loginwikimwuser-sessionId: Session

• Are you logged out on all wikis at the same time? If you use other devices (e.g. a mobile phone), are you logged out on those at the same time as well?

Yes. I do not use any other device.

• If you experience getting logged out again, the time range when it happened (the time when you opened a page and were logged out, and the last time before that when you opened a page and were still logged in, as accurately as you can remember).

Noticed when attempting to view a private abuse filter log on enwiki at 2024-09-11T00:26Z.

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?

The last wiki that I logged into was metawiki due to T372702#10109010.

• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

Yes

Following this, I logged into enwiki. Then I navigated to metawiki and had to click log in to also be logged in there.

This task is a concern for Temporary accounts project, in that once a user is logged out of their temporary account, there's no way to log back into it. Is it possible to instrument how often these unexpected logouts are happening, bucketed for named and temporary accounts?

I've also noticed recently that I've had to log in unexpectedly a few times. I happen to be a checkuser on enwiki, so I took advantage of that and ran a check on myself. Eliding the confidential data:

2024-09-10
14:41:45  RoySmith talk contribs block check Previously blocked Autopatrolled, Checkusers, Administrators Successfully logged in to Wikipedia as RoySmith
14:41:21  RoySmith talk contribs block check Previously blocked Autopatrolled, Checkusers, Administrators Successfully logged in to Wikipedia as RoySmith

2024-09-05
15:35:00  RoySmith talk contribs block check Previously blocked Autopatrolled, Checkusers, Administrators Successfully logged in to Wikipedia as RoySmith

2024-08-17
21:38:13  RoySmith talk contribs block check Previously blocked Autopatrolled, Checkusers, Administrators Successfully logged in to Wikipedia as RoySmith

2024-08-09
19:24:22  RoySmith talk contribs block check Previously blocked Autopatrolled, Checkusers, Administrators Successfully logged in to Wikipedia as RoySmith

There's no corresponding logout events, so this looks like the login sessions unexpectedly being lost. I have no clue why there's two in a row on 2024-09-10.

Hmmm, this is interesting. I'm using two different machines at home; a MacMini on my desktop and an old MacBook Pro that wanders around the house with me. All of these were on the MacBook.

Hi,

when I login I click on "Keep me logged in".

In dewiki and enwiki and the other wikipedia.org domain sites I stay logged in, but all several days I become logged out from commonswiki and metawiki and the other wikimedia.org domain sites.
Maybe it is a wikipedia.org / wikimedia.org thing? Does CentralAuth work fine?

My nickname is: user:Doc_Taxon

Please check, what's going wrong with logging out.

It just happened to me again. This time, I'm still logged in on my laptop, but logged out on my desktop.

Even stranger, I'm logged out on all of enwiki, commons, and wikidata, but I'm still logged in on https://wikitech.wikimedia.org; I thought that had been merged with the wikipedia single sign-on system?

And, yes, I have "keep me logged in for up to a year" checked.

In T372702#10144557, @RoySmith wrote:

Hmmm, this is interesting. I'm using two different machines at home; a MacMini on my desktop and an old MacBook Pro that wanders around the house with me. All of these were on the MacBook.

Strike that last observation; I think that's due to a checkuser oddity.

I keep getting logged out on my phone these days (while continuing to be logged in on my laptop), so I thought that it is some phone memory related trouble.

For the last 3 days, I am being signed out of en-wiki daily.

1. Last Saturday, I was signed in when I started an edit; but, when I published it I was signed out. After refreshing the page, I was centrally logged back in.
2. Sunday (yesterday) I was signed out when I opened my browser in the morning and had to enter my password again to sign in.
3. Today, I was signed in when I was typing a reply in a talk page; mid-way the preview started showing my IP instead of my signature and then had to enter my password again to sign in.

Till, last week I was only signed out once every 5-7 days for about a month, but now it's happening everyday.

Cross-referencing: T374184 and T374757 may or may not be the same issue (they are also problems with logging in, but with different symptoms).

This morning I was logged out on Commons (but not enwiki) on mobile and on all sites on my laptop. (6 days since last unexpected log out event)

Will note that I'm actively getting logged out every day or two, but logging in only requires me to press "Log in" and does not require me to enter a password. I am on Brave Browser.

It just happened to me again. As for cookies, I've got:

centralauth_Session     xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      meta.wikimedia.org      /       Session
centralauth_Token       xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      meta.wikimedia.org      /       2025-09-16T10:42:12.317Z
centralauth_User        RoySmith                              meta.wikimedia.org      /       2025-09-16T10:42:12.317Z
centralauth_ss0-Token   xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      meta.wikimedia.org      /       2025-01-13T18:01:13.580Z
centralauth_ss0-Token   xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      .wikipedia.org          /       2025-01-13T16:29:40.803Z
centralauth_ss0-User    RoySmith                              meta.wikimedia.org      /       2025-01-13T18:01:13.580Z
centralauth_ss0-User    RoySmith                              .wikipedia.org          /       2025-01-13T16:29:40.803Z
ss0-centralauth_Session xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      meta.wikimedia.org      /       Session
ss0-centralauth_Session xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      login.wikimedia.org     /       Session
ss0-centralauth_Session xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx      .wikipedia.org          /       Session

Just happened again in Firefox on Arch Linux. Was logged in, checkbox for keeping me logged in was checked, but I suddenly got logged out, only on the Dutch Wikipedia.

Getting the issue after a month again. I have been using mobile and laptop when i login to my laptop i got logout from my mobile and when i log in on my mobile and it caused logout from my laptop.

Now I got suddenly logged out again on Commons (Firefox, Arch Linux)…

I normally get logged out at random on random project sites. For example, one day I won't be signed in to Wikidata, while still being logged in to Wikipedia and Commons. It's not frequent, but it doesn't respect the 365 day period. When I get logged out again I will update this ticket.

Just happened to me again.

Logged out of Wikidata and Meta. Logging in to Phab gave me this error message, too:

Login Failure
Login cookie was set correctly, but your login session is not valid. Try clearing cookies and logging in again.

(I believe I clicked the Oauth button and it signed me in properly.)

• How frequently is it happening? (One hypothesis would be that login expires after 24 hours, which is the length data is retained in the central session store. Does that sound about right?)

~17 days since previous: T372702#10136205

• Is it correlated to some action you are taking, especially visiting another wiki which you have not visited for a while?

I clicked View more changes since [...] on my metawiki Special:Watchlist.

• Which of these cookies does your browser have? centralauth_Session, centralauth_Token, <wiki name>Session, <wiki name>Token (do NOT share the values of the cookies!) When will they expire? Extra useful if you can check right when you get logged out. (You can check in your browser's developer toolbar, e.g. on Chrome it's F12 and then select the Application tab, and the Cookies menu item on the left.)

centralauth_Session: not present, centralauth_Token: not present, <wiki name>Session: present, <wiki name>Token: not present
These are the expiries of all of the CA / wiki cookies present following the logout. centralauth_ss0-Token: 2025-01-15T15:22:42.954Z, centralauth_ss0-User: 2025-01-15T15:22:42.954Z, metawikiSession: Session, metawikiUserName: 2024-10-27T17:10:58.421Z, metawikimwuser-sessionId: Session, metawikiss0-UserID: 2025-01-15T15:22:42.954Z, metawikiss0-UserName: 2025-01-15T15:22:42.954Z

• Are you logged out on all wikis at the same time? If you use other devices (e.g. a mobile phone), are you logged out on those at the same time as well?

No, only metawiki. I do not use any other device.

• If you experience getting logged out again, the time range when it happened (the time when you opened a page and were logged out, and the last time before that when you opened a page and were still logged in, as accurately as you can remember).

Logged out at approximately 2024-09-28T17:45Z with my last logged in action at 2024-09-28T16:00Z.

• Is it happening on the same wiki where you logged in (ie. where you filled out a login form by entering your username and password) or only on other wikis?

The last wiki that I logged into was enwiki due to T372702#10136205.

• Are you sure you have set the "keep logged in" checkbox? If you don't do that, a login only lasting for 24 hours is normal. (More accurately, the login expires once you are inactive for half a day or so, but no sooner than 24 hours from login.)

Yes