Sometimes it happens to you that when you open your email app and see that the folders have vanished or are not accessible, there may be a possibility behind it, and it is not a permanent data loss.

In this article, we are going to discuss the causes of Thunderbird sub-folders not showing or Thunderbird folders inaccessible, and we will provide some fixes to resolve the problem.

If the issue persists after all basic and advanced troubleshooting, then this might be the time you want to consider migration with the help of SysTools Thunderbird to PST Converter. Let’s explore the causes behind it.

What Causes Thunderbird Sub-folders Not Showing?

#Thunderbird Extension Not Working

Sometimes extensions or add-ons that modify the folder didn’t adjust with the Thunderbird update, and when you see that your folder list has been changed after installing or updating an add-on. To fix this, you can run Thunderbird in Troubleshoot Mode (Help< Troubleshoot). This will disable the add-on, and if your folder comes back after this, then the extension is the issue.

#Fix Thunderbird add-ons Issue by Disabling Selectively

Once you know that the add-on is the culprit, then you can disable them one by one and restart Thunderbird until your folder works normally, and as you know, the add-on is the issue, then you can remove it, replace it with a new one, or contact your developer to check if they are offering any updates. It might fix the Thunderbird folders not showing issue.

#Folder Size, Hidden Data, and Compacting resolve Thunderbird folders not showing

Sometimes, the folders that contain thousands of messages or are stuffed with hidden/deleted content can be the reason for slow or blocked access. This can be the reason you see that the folders have vanished, but actually the Thunderbird can’t load them. On Interval time, right-click folders< Compact for problem folders use Properties< Repair folder to restore the normal access.

#Server Sync Problems and Local Cache Issues

Once the folders appear in the list, there is a possibility that they display as empty because the local cache didn’t download properly, or the server changed the subscription state. Right-click the account< Synchronise and Disk space< Download Now and double check server-side web mail to confirm the folder still exists.

Rescue Steps When Normal Fixes Fail to Resolve Thunderbird Folders Not Showing Issue

#Rebuild Indexes and Refresh the Profile

If the issue still persists after the normal fixes, then close Thunderbird. Locate your profile via help< Troubleshooting information<open folder. Delete or rename global.messages-db.sqlite and the .msf files corresponding to the missing folders. After the restart, Thunderbird rebuilds the indexes automatically. Usually, this restores both parent folders and nested sub-folders.

#Backup and Convert Mailbox Data to Safeguard

After doing all the above steps, the issue persists, and it is wasting your time. The smart choice is to create a safe backup with tools like SysTools MBOX to PST Converter. By doing this, you can safely and securely export your Thunderbird folders, sub-folders, emails, and attachments into PST or other formats. This ensures that if your Thunderbird profile fails, then you have your data saved.

#Create a Fresh Profile and Migrate Data to sort out Thunderbird Folders Not Showing Issue

If your existing profile gets corrupted, you may choose to create a new Thunderbird profile using the profile manager. Then add your accounts, and if everything works, then you can import your exported PST or re-add old data via the converter tool or manually, but in the manual approach, you may lose your data.

Final Thoughts

If Thunderbird folders not showing or Thunderbird folders are inaccessible, and your work depends on the folders and sub-folders. There is no need to worry as the issues are fixable with the manual steps that we have shared with you but there is a possibility that you may lose your data with the manual method, the best and wise thing is to back up your data using the tools we have mentioned above for a smooth and secure back and if the Thunderbird is corrupted then you can migrate the data to PST or other format after backing up your data this is the best and secure root to keep your data safe and get a fresh start.