This issue has effected some people and has been reported as a bug. Bug report just in case you wanted to follow it:

• https://bugzilla.mozilla.org/show_bug.cgi?id=1990571

It seems to effect those who have a deeper hierachy of folders and subfolders OR/AND may have installed Thunderbird from the 'Windows app store' which does not use the standard location, so is much longer.

Thunderbird downloaded from: https://www.thunderbird.net/en-US/thunderbird/all/ Uses the following as a default location for profile:

• C://Users/<username>/Appdata/Roaming/Thunderbird/Profiles/<profile name>/ etc

Thunderbrd installed from the 'Windows App Store' uses the following as a default location for profile:

• C://Users/<username>/AppData/Local/Packages/MozillaThunderbird.MZLA_h5892qc0xkpca/LocalCache/Roaming/Thunderbird/Profiles/<profile name>/ etc

Advise at the moment is to try the following first as it has worked for others. Look at the various folder names and see if you can rename to use less characters. Especially for any folders with subfolders that seem effected. Example senarios:

• Folder name: 'Online Orders' rename as 'Orders' - this will save 7 chararcter as a space is also deemed as a character.
• Folder name: 'Marks and Spencer' rename as 'M&S' - saving 14 chars
• Folder name : 'Thunderbird Support' rename as 'TBird Help' or even just 'TBird'

IMPORTANT Before you alter anything could you access the 'Error Console' Tools > Developer Tools > Error Console

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