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Some empty mail folders after Thunderbird migration.

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  • Last reply by venco5

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I've migrated Thunderbird profile with lot of local folders to a new Windows computer, and almost everything works fine. However, few folders are shown empty in Thunderbird, and they certainly have some mail - I can see it in the corresponding files. When I look at a problematic folder properties it shows that its location is different from the actual file - some random 8 letters, and Thunderbird created an empty folder with this name. I've tried to remove folderTree.json, folderCache.json, and even global-messages-db.sqlite, and restarted the Thunderbird. The properties of the folder remain the same and the directory with wrong name is created again, and the folder remains empty. Other mail folders are fine - the emails are rescanned.

Where the mapping from local mail file name to Properties/Location is stored? I cannot find it with grep - the only reference I've found was in the files I removed, but the mapping somehow persists.

I've migrated Thunderbird profile with lot of local folders to a new Windows computer, and almost everything works fine. However, few folders are shown empty in Thunderbird, and they certainly have some mail - I can see it in the corresponding files. When I look at a problematic folder properties it shows that its location is different from the actual file - some random 8 letters, and Thunderbird created an empty folder with this name. I've tried to remove folderTree.json, folderCache.json, and even global-messages-db.sqlite, and restarted the Thunderbird. The properties of the folder remain the same and the directory with wrong name is created again, and the folder remains empty. Other mail folders are fine - the emails are rescanned. Where the mapping from local mail file name to Properties/Location is stored? I cannot find it with grep - the only reference I've found was in the files I removed, but the mapping somehow persists.

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venco5 said

I've migrated Thunderbird profile with lot of local folders to a new Windows computer, and almost everything works fine. However, few folders are shown empty in Thunderbird, and they certainly have some mail - I can see it in the corresponding files. When I look at a problematic folder properties it shows that its location is different from the actual file - some random 8 letters, and Thunderbird created an empty folder with this name. I've tried to remove folderTree.json, folderCache.json, and even global-messages-db.sqlite, and restarted the Thunderbird. The properties of the folder remain the same and the directory with wrong name is created again, and the folder remains empty. Other mail folders are fine - the emails are rescanned. Where the mapping from local mail file name to Properties/Location is stored? I cannot find it with grep - the only reference I've found was in the files I removed, but the mapping somehow persists.

The path to folders is derived from the account directory in account settings plus the appropriate additions of folder names. Generally this stuff is not hard coded, it is hard coded after folk set it to something other than it's default usually.

Modified by Matt

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The path to folders is correct - most of the folders are shown without problem. It's only few of the files in the profile Mail folder are shown as empty. The corresponding files are not empty, but the folder Properties/Location field show that the specific folder location is not equal to corresponding file, but have its name part replaced with randomly looking 8 symbols - bcfdd710 for example.

So, for the folder that's fine Thunderbird shows Properties/Location as "mailbox:///C:/Users/UserName/AppData/Roaming/Thunderbird/Profiles/profile-dir/Mail/Local Folders/Info" for example (I've changed user and profile name). But, the folder that's shown as empty in Thunderbird has the location as "mailbox:///C:/Users/UserName/AppData/Roaming/Thunderbird/Profiles/profile-dir/Mail/Local Folders/bcfdd710/" where the "bcfdd710" part isn't equal to the mail file name, and I don't know where the "bcfdd710" comes from.

Oh, I've just noticed that all problematic folders have non-ASCII symbols in their file name, could it be the cause the problem? There was no problem on the Windows I've migrated from, but maybe some system-wide configuration could affect that?

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Apparently non-ASCII symbols in mail file name are the culprit. For some reason Thunderbird rejects this name or rather generate another name from it (hash?) and then creates folder with generated name and forgets about the original file. So, as a workaround, I've renamed the files to some ASCII version, and then renamed the folders inside Thunderbird to the desired non-ASCII names back.