Thunderbird Error: The Connection to Server Was Reset

Thunderbird may sometimes throw an error that says the connection to the server was reset. This error message can take users by surprise. Usually, it occurs all of a sudden without any tell-tale signs.

If you’re looking for a solution to fix this problem, you’ve got a series of potential solutions below.

How to Fix Thunderbird Server Connection Was Reset

Turn Off Email Shield in AVG Antivirus

Many users noticed the server reset error occurred mainly on computers running AVG Antivirus. It seems the error is triggered by a conflict between the two programs.

Disabling the AVG Email Shield solved this problem for many users. Go to Basic Protection and disable the Email Shield.

However, you need to turn off the Email Shielf every time you power up your computer. Apparently, the error re-appears after every shutdown. So, this is only a temporary workaround. But it’s a handy one nevertheless.

Reinstall AVG

Reinstall AVG and check if this solves the problem. Maybe some AVG files got corrupted. Check if the server connection still gets reset with a fresh copy of AVG installed.

1. To uninstall AVG, launch the Control Panel.
2. Click on Programs and Features.
3. Then select Uninstall a program.
4. Select AVG and click on the Uninstall button.
5. Restart your computer.
6. Download AVG again and install the program.

Disable Your Antivirus

If you’re using a different antivirus, disable it and test if you’re still getting the same error on Thunderbird.

If the antivirus you’re using has a built-in email shield similar to AVG’s, go ahead and disable it. You can also whitelist Thunderbird in your antivirus settings.

The steps to follow are different for each antivirus tool. For detailed instructions, go to your antivirus official support page.

Edit the Network DNS Settings

Changing the network DNS settings is a solution that worked for many users. You can either disable IPv6 or accept only IPv4 domains.

1. Launch Thunderbird and click on Options.
2. Then select General.
3. Scroll down to Config Editor (lower right-hand corner).
4. Accept the risks of changing the settings.
5. Type IP in the search box and locate the settings below. Use only one of the two variants:
   • network.dns.disableIPv6. Set it to True.
   • network.dns.ipv4OnlyDomains. Set it to gmail.com.

The network.dns.isableIPv6 setting is simpler to use than setting the domain to Gmail. So, if you want a simpler solution, edit the IPv6 setting.

Then close Thunderbird and launch it again. Check if this method ironed out the error.

Disable Your VPN

If you’re using a VPN program, go ahead and disable it. Many users solved this problem by simply turning off their VPN.

It seems that VPN tools, and NordVPN particularly, often interfere with Thunderbird.

If nothing worked, you may want to temporarily switch to a different email service. Maybe Thunderbird is affected by a server problem that Mozilla has yet to acknowledge. Check if other users complained about the same problem recently.

Let us know if your connection to the email server is stable now. Do tell us which solution worked for you!