"Invalid UID Fetch attribute XSENDER"

[The_Peregrine]

Good afternoon:

I'm experiencing the same issue on my work machine. I'm only noticing it as of this morning but as yesterday was a civic holiday in my jurisdiction it is possible that it has been happening for several days and I have been unaware. I have had some luck by closing the process through the task manager and reopening but this does not consistently fix the issue. Any suggestions greatly appreciated.

[mh_76]

Just tested on Outlook2016 / Win10 (partitioned MacBook Pro) and no problem. I'm not sure if that's using an app-specific password or my regular one. Thunderbird / Mac worked with the app-specific one and doesn't work at all with my regular password). Ports on Outlook/Win are the same, except that send encryption is set to STARTTLS (I don't remember if that was the default or if I set it up that way for some reason). Thunderbird / Mac worked with 2-step authentication enabled but I switched to 2-factor yesterday. I thought that the app-specific passwords were supposed to bypass that. nkh08, SeaMonkey is a Mozilla product so I wonder if the issue is Mozilla-wide?

[fred9999]

Best suggestion thus far is to find an alternate email client until this issue is resolved, likely by Apple. I'm now running Opera on Win with no problem (all apple standard incoming / outgoing, with app specific password). That appears to also run on Mac and Linux.

My Apple contact has a day off today, I've left him a message to see if this issue got escalated.

BTW: I think as of a month or two ago, all third party apps must enable the app-specific password to access iCloud data.

[qwertyz1237]

I had the same problem using Linux & Thunderbird 52.0.2. Twiddling the Account Settings -> Server Settings -> Security Settings as marklark did got things working for me, at least for today. We'll see if it holds up for tomorrow.

[nurd]

Same problem here. Running TB 52.2.1 on a Mac, icloud account w 3rd party app pw, fred9999 is right, for over a month now. All working fine until yesterday... the warning message popped up over and over. I had to force quit TB. I do get email with a Subject but body is blank and then alert messages start popping up. When trouble shooting I forgot about the 3rd party software. Deleted the pw because I didn't recognize it and kept trying to put my icloud pw in. Then I remembered about the 3rd party PW, retrieved it from the Icloud site. After successfully logging on I got 1 email w no problem. After that it started back again. Searched web and found it's not only me. Misery loves company. I'll use workaround for now.

[nurd]

Thanks qwertz1237, marklark, i switched the security from SSL/TLS to StartTLS and got "could not connect to server" switched back to SSL/TLS and now can see messages and working as before. Keep fingers crossed.

[mh_76]

That works for me right now so seems to be at least a temporary fix, will see tomorrow. Mac Mail, iPhone, iPad all still work normally too.

[Mo99]

Same here, Win 7, TB 52.2.1 (German) - switching between different connection settings doesn't help in my case

[Mo99]

I've just tried TB 56.0b1 (beta version) - but also without success

[nkh08]

nkh08, SeaMonkey is a Mozilla product so I wonder if the issue is Mozilla-wide?

Would seem so. The suggested "switch the connection setting" fix seems to have done the trick for the time being.

[mh_76]

The security setting switch is a temporary fix...just logged in and the error has returned. Looks like the switch/switch back needs to be re-done every time you start Thunderbird. On the plus side, Thunderbird didn't crash this morning as it often does. Fingers crossed.

[omnichad]

It seems this morning that the problem has suddenly resolved itself. Has this been the case for anyone else? Maybe Apple finally caught their mistake and fixed it.

[hheckiii]

I also have this issue.
Windows 10 Pro version 1703 64-bit
Thunderbird version 52.2.1 32-bit

[oneplane]

Just piling on here: same problem, me.com/icloud IMAP account, two Macs with Thunderbird, both having "Invalid UID Fetch attribute XSENDER" errors, using app-specific passwords, 2FA is on, but it's probably not relevant and auth works fine, it's those IMAP commands that fail.

[fred9999]

cross fingers: as of this time, it appears to be working. Anyone else still having issues? I have a call with Apple Support tonight, and I will report findings.