Pretty sure the uncaught exception error is unrelated. Will need to look for another cause.

still have this problem.....

I have this issue on both Win7 x64 and Win 10 x64 machines - Using TB 60.9.1 (32-bit) on both. Error seems to occur when deleted messages are synched with server. Error source is JAVA Jar file Autosync.js - Seems to result from code in this area - // if this is the last folder of this server in the queue

       // create a sync event and clean the sync start time
       let found = false;
       for (let value of this._syncInfoPerFolder.values())
       {
         if (value.syncFolder.server == folder.server)
         {
           found = true;
           break;
         }
       }

TB slows to a crawl & basicly stalls. No other errors are indicated and this same error shows in the "error console" each time.

etc45 said

I have this issue on both Win7 x64 and Win 10 x64 machines - Using TB 60.9.1 (32-bit) on both. Error seems to occur when deleted messages are synched with server. Error source is JAVA Jar file Autosync.js - Seems to result from code in this area - ... TB slows to a crawl & basicly stalls. No other errors are indicated and this same error shows in the "error console" each time.

Good initiative on forensics. But to rephrase about "uncaught exception .. autosync.js", it is a red herring and may be ignored.

Please retry with Windows started in safe mode. If you still have a problem please create a new topic for your issue https://support.mozilla.org/en-US/questions/new/thunderbird

my issue was with Avast virus scanner - removed this and it worked fine again

suetown, thanks for the follow up post with the answer - I wish every reporter was kind enough to do so.