Did you leave the category setting at "Get Add-ons"? I cannot think of any other reason why opening the add-ons window would try to go online. You can change the category to Extensions to get around the problem. From Options > Advanced > General > Config Editor, look up category and change the setting value for "extensions.ui.lastCategory" to "addons://list/extension". Then you should be able to open that window without a problem.

Can you post a screenshot of the error? http://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

swedish

När Thunderbird startar får jag detta meddelande:

"Säker anslutning misslyckades

live.mozillamessaging.com använder ett ogiltigt säkerhetscertifikat. Certifikatet är inte betrott eftersom certifikatkedjan till utfärdaren saknas. (Felkod: sec_error_unknown_issuer)

   Detta kan bero på ett problem med serverns konfiguration, eller så kanske någon annan felaktigt utger sig för att vara servern.
   Om du tidigare utan problem har anslutit till den här servern kanske felet är tillfälligt och du kan försöka igen senare.

Eller så kan du lägga till ett undantag…"

"Hämta tillägg" ger detta meddelande:

"Säker anslutning misslyckades

services.addons.mozilla.org använder ett ogiltigt säkerhetscertifikat. Certifikatet är inte betrott eftersom certifikatkedjan till utfärdaren saknas. (Felkod: sec_error_unknown_issuer)

   Detta kan bero på ett problem med serverns konfiguration, eller så kanske någon annan felaktigt utger sig för att vara servern.
   Om du tidigare utan problem har anslutit till den här servern kanske felet är tillfälligt och du kan försöka igen senare.

Eller så kan du lägga till ett undantag…"

Vad menas med "lägga till ett undantag" Var gör jag det i så fall?

Ovanstående felmeddelanden i Thunderbird får jag bara i min Windows 8.1-dator - inte i XP eller Vista.

english

When Thunderbird starts, I get this message:

"Secure Connection Failed

live.mozillamessaging.com uses an invalid security certificate. The certificate is not trusted because the certificate chain to the issuer missing. (Error code: sec_error_unknown_issuer)

     This may be due to a problem with the server's configuration, or maybe someone else mistakenly claims to be the server.      If you have no problems connecting to this server might drop is temporary and you can try again later.

Or you can add an exception ... "

"Get add-ons" gives this message:

"Secure Connection Failed

services.addons.mozilla.org uses an invalid security certificate. The certificate is not trusted because the certificate chain to the issuer missing. (Error code: sec_error_unknown_issuer)

     This may be due to a problem with the server's configuration, or maybe someone else mistakenly claims to be the server.      If you have no problems connecting to this server might drop is temporary and you can try again later.

Or you can add an exception ... "

What does "add an exception" Where do I do it then?

The above error messages in Thunderbird I just get in my Windows 8.1 computer - not in XP or Vista.

Chances are you picked up some sort of malware intercepting your secure connection. You'll need to find out the issuer of the cert you get.

Please attempt to add a security exception at the bottom of the error page and inspect the certificate (see attached screenshot for instructions). Do not actually confirm the security exception.

Who is the issuer of the cert? Please post a screenshot of the certificate viewer window.

I only got this ( se dump) and the computer is new - no malware.

I only got this ( se dump) and the computer is new - no malware.

Click the 'Or you can add an exception' link at the bottom of the error message and follow the instructions above.

I click and click but nothing happens. Right clicking gives a menu of choices: Open link in browser / Select All / Copy link address.

Do you have a software BrowserSafe, Browser Safeguard, or Safeguard installed? Please check the Windows Control Panel, Uninstall a Program. Clicking the "Installed on" column heading will bring the most recent items to the top. This is also helpful in revealing unexpected bundled programs installed together.

None of the software is installed. However, I have McAfee Live Safe -Internet Security enabled in the default settings.

Check your McAfee settings. Look for something like 'Safe Search and Surf'. Disable it.

Have tried turning off the firewall. It did not help. Closed all of which can influence but without result. Is the problem that Thunderbrd does not work perfectly with Windows 8.1 64 bit?

I have no idea about McAfee. The most likely scenario is that some sort of 'security' function built into McAfee is trying to intercept your secure connection. You should contact McAfee support about this.

The problem is solved. The cause was malware Adware Rocket Tab that changed something in the proxy settings. The program SpyHunter cleaned my computer and restored the proxy. Thunderbird now works perfectly.