Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Thunderbird fails to connect to the server

more options

Thunderbird 78.5.1 On computer A, probably since one of the latest updates TB is not able anymore to connect to the server, I only get the error message "connection to server xxx failed"

Activity manager shows no messages at all Server xxx is on my network, connection is not blocked TB profile seems to be ok : when using the same profile on computer B, everything is working fine

  • creating new account (same data as existing account) on new profile on computer A is not possible : message "Unable to log in at server. Probably wrong configuration, username or password"
  • however using exactly same procedure and data on computer B, it is working !

So, creating a new account on a new profile is not possible Disabling firewall and AV : no change TB safe mode : no change Reinstalling and uninstalling/installing TB again : no change Windows safe mode with Networking : no change TB config:security.tls settings are identical on computer A and B I changed TB config:security.tls settings : .version.min to 2, 1 and 0 : no change

and .enable_post_handshake_auth to true : no change
and .version.enable-deprecated = true : no change
(all after restarting TB)

Changing TB Server Security settings : no change

I deleted the stored passwords, but after restarting TB is NOT asking for the pw's meaning TB is even NOT trying to connect to the server ?

(error messages are translated from Dutch, so possibly not identical to English ones)

see also https://support.cdn.mozilla.net/en-US/questions/1304493 https://support.mozilla.org/en-US/questions/1269090?page=2 https://support.mozilla.org/nl/questions/1313268

I think I tried almost everything to solve the problem. It seems the problem is on the computer/TB installation, but where ? Can someone tell me how to proceed further ?

Thunderbird 78.5.1 On computer A, probably since one of the latest updates TB is not able anymore to connect to the server, I only get the error message "connection to server xxx failed" Activity manager shows no messages at all Server xxx is on my network, connection is not blocked TB profile seems to be ok : when using the same profile on computer B, everything is working fine * creating new account (same data as existing account) on new profile on computer A is not possible : message "Unable to log in at server. Probably wrong configuration, username or password" * however using exactly same procedure and data on computer B, it is working ! So, creating a new account on a new profile is not possible Disabling firewall and AV : no change TB safe mode : no change Reinstalling and uninstalling/installing TB again : no change Windows safe mode with Networking : no change TB config:security.tls settings are identical on computer A and B I changed TB config:security.tls settings : .version.min to 2, 1 and 0 : no change and .enable_post_handshake_auth to true : no change and .version.enable-deprecated = true : no change (all after restarting TB) Changing TB Server Security settings : no change I deleted the stored passwords, but after restarting TB is NOT asking for the pw's meaning TB is even NOT trying to connect to the server ? (error messages are translated from Dutch, so possibly not identical to English ones) see also https://support.cdn.mozilla.net/en-US/questions/1304493 https://support.mozilla.org/en-US/questions/1269090?page=2 https://support.mozilla.org/nl/questions/1313268 I think I tried almost everything to solve the problem. It seems the problem is on the computer/TB installation, but where ? Can someone tell me how to proceed further ?

Modified by Tom

Chosen solution

Problem resolved ! 'spontaneously' after updating 78.5.1 > 78.6.0 , done nothing else ... So something would have been wrong in TB and corrected by this update, I suppose ? Everybody thanks to try to help me !

@ День сумо : I only got a mail with your initial message and was not aware of the edit later on.

Read this answer in context 👍 0

All Replies (9)

more options

How about we start at the beginning. I tried reading you see also. But the incompetence in the first I was reading simply made me angry so I stopped. I did not read anything at all that made me think anyone had any idea at all whet they were doing. I simply do not have any interest in reading about group of folk just trying random stuff because it worked for someone else. The second appear to be related to apple products so unlikely your windows 10 has an Apple cleanup tool

So some diagnostic suggestions

  • Open a command window and ping the server, both as named and using the IP address of the server. What were the results? DNS issues are very common on local networks. So different result will point to those
  • Do you have an anti virus or software firewall? If so restart windows in safe mode with networking and see if connectivity works. This is often the root of connectivity issues. This is especially so with ESET at the moment. MAjor issues there post December 1st
  • Do you have a VPN? If so your email connections will be leaving your network on it and trying to come back and probably refused by the firewall.
  • Have you tried connecting with a normal password and no connection security? BTW doing so bypasses all of the changes in TLS you have apparently randomly changed to see if it might be an issue.
  • Have you checked to localhosts file in windows is not poisoned with incorrect information.
  • if you open the error console (ctrl +Shift +J ) and clear it (trash icon) and attempt to get mail again is there anything appearing.

Last if none of the other stuff looks like it might be helping. log the connection. https://wiki.mozilla.org/MailNews:Logging Log files get very large very quickly so a quick startup and shut down would be indicated. They are quite detailed and difficult to read (but text files). but they can offer a wealth of information. I do suggest specialist text editors like notepad++ as windows notepad struggles if the files get to big and using word or write converts the text

more options

Hi Matt, thanks for swift replying (being angry). I just looked for similar problems to try to resolve mine.

  • The server is pingable by ip and by name : Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms.
  • Ports 143 and 587 on the server are reachable and listening (MS tool PortQry).
  • Comodo AV and FW disabled : problem not solved.
  • Windows in safe mode with NW : problem not solved.
  • no VPN
  • Connecting with a normal pw and no connection security : problem not solved.
  • hosts file is empty
  • Nothing appears in the error console when trying getting mail. I only get the small window in the lower left corner "connection to server xxx failed".
  • I logged the connection (MOZ_LOG=IMAP:5,timestamp / real user and server names modified) only opening TB, 'get new messages', clicking on a folder and closing TB. But I don't know how TB can try to connect because all stored pw's are deleted and TB does NOT ask for ?

Hope you can help me further.

2020-12-13 14:18:59.851000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop entering [this=2BAF5000] 2020-12-13 14:19:00.036000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop entering [this=3E3A9000] 2020-12-13 14:19:00.073000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop entering [this=2CBB6000] 2020-12-13 14:19:00.174000 UTC - [(null) 1688: Main Thread]: I/IMAP 2BAF5000:servername:NA:SetupWithUrlCallback: clearing IMAP_CONNECTION_IS_OPEN 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:ProcessCurrentURL: entering 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:ProcessCurrentURL:imap://username%40servername%2Elocal@servername:143/select%3E/z%20Mappen/Duiken/actueel: = currentUrl 2020-12-13 14:19:00.174000 UTC - [(null) 1688: Main Thread]: I/IMAP 3E3A9000:servername:NA:SetupWithUrlCallback: clearing IMAP_CONNECTION_IS_OPEN 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:ProcessCurrentURL: entering 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:ProcessCurrentURL:imap://username%40servername%2Elocal@servername:143/select%3E/INBOX: = currentUrl 2020-12-13 14:19:00.174000 UTC - [(null) 1688: Main Thread]: I/IMAP 2CBB6000:servername:NA:SetupWithUrlCallback: clearing IMAP_CONNECTION_IS_OPEN 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:ProcessCurrentURL: entering 2020-12-13 14:19:00.174000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:ProcessCurrentURL:imap://Wij%40servername%2Elocal@servername:143/select%3E/INBOX: = currentUrl 2020-12-13 14:19:00.521000 UTC - [(null) 1688: IMAP]: D/IMAP ReadNextLine [rv=0x804b001e stream=292072E0 nb=0 needmore=0] 2020-12-13 14:19:00.521000 UTC - [(null) 1688: IMAP]: D/IMAP ReadNextLine [rv=0x804b001e stream=2D2700A0 nb=0 needmore=0] 2020-12-13 14:19:00.521000 UTC - [(null) 1688: IMAP]: D/IMAP ReadNextLine [rv=0x804b001e stream=2D270100 nb=0 needmore=0] 2020-12-13 14:19:00.575000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 804b001e 2020-12-13 14:19:00.575000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 804b001e 2020-12-13 14:19:00.590000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 804b001e 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:TellThreadToDie: close socket connection 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:CreateNewLineFromSocket: (null) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP URL failed with code 0x804b001e (imap://username%40servername%2Elocal@servername:143/select%3E/z%20Mappen/Duiken/actueel) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:TellThreadToDie: close socket connection 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:CreateNewLineFromSocket: (null) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP URL failed with code 0x804b001e (imap://username%40servername%2Elocal@servername:143/select%3E/INBOX) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:TellThreadToDie: close socket connection 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:CreateNewLineFromSocket: (null) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e) 2020-12-13 14:19:00.637000 UTC - [(null) 1688: IMAP]: D/IMAP URL failed with code 0x804b001e (imap://Wij%40servername%2Elocal@servername:143/select%3E/INBOX) 2020-12-13 14:19:00.769000 UTC - [(null) 1688: IMAP]: I/IMAP 2BAF5000:servername:NA:ProcessCurrentURL: aborting queued urls 2020-12-13 14:19:00.775000 UTC - [(null) 1688: IMAP]: I/IMAP 3E3A9000:servername:NA:ProcessCurrentURL: aborting queued urls 2020-12-13 14:19:00.791000 UTC - [(null) 1688: IMAP]: I/IMAP 2CBB6000:servername:NA:ProcessCurrentURL: aborting queued urls 2020-12-13 14:19:00.822000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop leaving [this=2BAF5000] 2020-12-13 14:19:00.822000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop leaving [this=3E3A9000] 2020-12-13 14:19:00.822000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop leaving [this=2CBB6000] 2020-12-13 14:19:15.448000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop entering [this=06E29000] 2020-12-13 14:19:15.448000 UTC - [(null) 1688: Main Thread]: I/IMAP 06E29000:servername:NA:SetupWithUrlCallback: clearing IMAP_CONNECTION_IS_OPEN 2020-12-13 14:19:15.448000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL: entering 2020-12-13 14:19:15.448000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL:imap://username%40servername%2Elocal@servername:143/select%3E/INBOX: = currentUrl 2020-12-13 14:19:15.448000 UTC - [(null) 1688: IMAP]: D/IMAP ReadNextLine [rv=0x804b001e stream=18B0EF40 nb=0 needmore=1] 2020-12-13 14:19:15.463000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 804b001e 2020-12-13 14:19:15.463000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:TellThreadToDie: close socket connection 2020-12-13 14:19:15.463000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:CreateNewLineFromSocket: (null) 2020-12-13 14:19:15.463000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e) 2020-12-13 14:19:15.463000 UTC - [(null) 1688: IMAP]: D/IMAP URL failed with code 0x804b001e (imap://username%40servername%2Elocal@servername:143/select%3E/INBOX) 2020-12-13 14:19:15.479000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL: aborting queued urls 2020-12-13 14:19:15.495000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop leaving [this=06E29000] 2020-12-13 14:19:20.488000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop entering [this=06E29000] 2020-12-13 14:19:21.043000 UTC - [(null) 1688: Main Thread]: I/IMAP 06E29000:servername:NA:SetupWithUrlCallback: clearing IMAP_CONNECTION_IS_OPEN 2020-12-13 14:19:21.043000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL: entering 2020-12-13 14:19:21.043000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL:imap://username%40servername%2Elocal@servername:143/select%3E/INBOX: = currentUrl 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: D/IMAP ReadNextLine [rv=0x804b001e stream=2A774EE0 nb=0 needmore=0] 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 804b001e 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:TellThreadToDie: close socket connection 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:CreateNewLineFromSocket: (null) 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e) 2020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: D/IMAP URL failed with code 0x804b001e (imap://username%40servername%2Elocal@servername:143/select%3E/INBOX) 2020-12-13 14:19:21.074000 UTC - [(null) 1688: IMAP]: I/IMAP 06E29000:servername:NA:ProcessCurrentURL: aborting queued urls 2020-12-13 14:19:21.089000 UTC - [(null) 1688: IMAP]: D/IMAP ImapThreadMainLoop leaving [this=06E29000]

more options

Nobody able to help me further ?

more options

Hello there atom. We have read your message. We try to help you.

I m going to read your questions. Please wait a minute.


Can you tell us where you are, does this take place in an office or home where several computers, telephones, (are you using a server)etc. are present?

Multiple Routers or Modems?

It sounds like a VPN connection .... Or a network error on a card.

Can you try another type of version of the Thunderbird software.(Cause -Can be reported as a bug). Then send us a message. Refresh the operating system. (If possible).

https://releases.mozilla.org/pub/thunderbird/releases/


Greetings Firefox Volunteer.

Modified by День сумо

more options

020-12-13 14:19:21.058000 UTC - [(null) 1688: IMAP]: D/IMAP SetConnectionStatus(0x804b001e)

Google 0x804b001e and you get https://james-ross.co.uk/mozilla/misc/nserror?0x804B001E "unknown host"

SO it looks like you have DNS or name resolution issues (DNS OR Firewall) have you enabled dns over HTTP in Thunderbird? That you tried clearing the cache in Windows?

more options

Hi Matt,

  • I don't think DNS over HTTP is enabled in TB. At Options - Connection Settings only 'detect proxy settings for this network automatically' (or something similar) is selected. All other settings are blank or not selected.
  • Clearing the DNS cache in Windows (ipconfig/flushDNS) didn't change anything.
more options

Chosen Solution

Problem resolved ! 'spontaneously' after updating 78.5.1 > 78.6.0 , done nothing else ... So something would have been wrong in TB and corrected by this update, I suppose ? Everybody thanks to try to help me !

@ День сумо : I only got a mail with your initial message and was not aware of the edit later on.

more options

I don't see anything in the release notes or security fixes that would account for it. But goodo. As long as it works. Release notes https://www.thunderbird.net/en-US/thunderbird/78.6.0/releasenotes/ Security fixes https://www.mozilla.org/en-US/security/advisories/mfsa2020-56/

Modified by Matt

more options

Hello there again We have read your message.

Thanks you for using Thunderbird.

Have a good Christmas all you guys.





Greetings Firefox Volunteer.

Modified by День сумо