Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

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 78.6.1

  • 2 ŋuɖoɖowo
  • 1 masɔmasɔ sia le esi
  • 10 views
  • Nuɖoɖo mlɔetɔ expilot3

I just installed the new Thunderbird 78.6.1 and when it re-opened, in the left column, in between my two e-mail accounts there are over 100 lines that say popstate-xx.dat (xx is a different number in each case). It takes forever to scroll from my first account to the next one with all these things in between them. What are these? Can they be deleted safely? Will they keep coming back?

I just installed the new Thunderbird 78.6.1 and when it re-opened, in the left column, in between my two e-mail accounts there are over 100 lines that say '''popstate-xx.dat''' (xx is a different number in each case). It takes forever to scroll from my first account to the next one with all these things in between them. What are these? Can they be deleted safely? Will they keep coming back?

All Replies (2)

THey indicate Thunderbird is having issues accessing the files on your hard disk that it created. Perhaps the most probably cause is anti virus scanning of files in your profile folder within Thunderbird.

These popstate.dat files are used by Thunderbird to determine which emails have been downloaded in a pop mail acocunt and only one should exist. Without the numbers. So yes you can delete them, but they will come back unless you fix the cause of them appearing in the first place.

Well, I have just spent twenty minutes deleting and have hardly made a dent. There are over 900 of the damn things. Never had a problem prior to this "New and improved" version. This sucks.