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

Avatar for Username

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
Open

Thunderbird 159.0 manual backup throwing filename too long messages

Thunderbird Profiles
david replied am na 12 waxtu
MazdaKen
MazdaKen

I am attempting to migrate my Win-10 Thunderbird v159.0 to a new Win-11 installation. The current profile folder size is too large for the automatic backup process (6.2 GB), so I am creating a copy of the profile folder structure. When I copy the profile folder structure into the copy buffer, no errors are shown. But, when I attempt to paste into a new folder, I am getting 13 messages regarding the filenames are too long for both sbd and mozmsgs filenames. Is there a maximum local folder name and/or local filenames limit. I can see where I can control the local folder name length, but not the local filename (email) name length.

There are 5 profile folders listed under the Profiles folder, their contents as follows: Profile Name Folder Count File Count Storage k1fx5scw.default 1,211 folders 24,946 files 3.78 GB (appears to be current default) 5zo1yxiu.default-release-1 17 folders 87 files 14.8 MB k1fx5scw.default.old 937 folders 21,555 files 2.29 GB (previous incarnation of default) rpsz3c78.default-release 14 folders 45 files 14.2 MB lhqhc5hj.default 0 folders 1 file 47 bytes

I am attempting to migrate my Win-10 Thunderbird v159.0 to a new Win-11 installation. The current profile folder size is too large for the automatic backup process (6.2 GB), so I am creating a copy of the profile folder structure. When I copy the profile folder structure into the copy buffer, no errors are shown. But, when I attempt to paste into a new folder, I am getting 13 messages regarding the filenames are too long for both sbd and mozmsgs filenames. Is there a maximum local folder name and/or local filenames limit. I can see where I can control the local folder name length, but not the local filename (email) name length. There are 5 profile folders listed under the Profiles folder, their contents as follows: Profile Name Folder Count File Count Storage k1fx5scw.default 1,211 folders 24,946 files 3.78 GB (appears to be current default) 5zo1yxiu.default-release-1 17 folders 87 files 14.8 MB k1fx5scw.default.old 937 folders 21,555 files 2.29 GB (previous incarnation of default) rpsz3c78.default-release 14 folders 45 files 14.2 MB lhqhc5hj.default 0 folders 1 file 47 bytes

All Replies (3)

david
david
  • 10 jàppalekat yi jiitu

That is a windows issue, not a thunderbird one. Windows is adding the length of the file being pasted to the location of the receiving folder. what is the location of the receiving folder? I am assuming it to be c:\users\<yourid>\appdata\roaming.

A possibility that may bypass this: If the large folders are IMAP message folders, you could do this:

  1. exit thunderbird
  2. locate the large IMAP message folders, eg. inbox,inbox.msf, etc. and delete them.

That should reduce the profile folder such that the copy is easy. You can then follow these steps:

BACKUP

  1. ensure thunderbird is not running on old PC
  2. enter %appdata% in search window on task bar and press Enter key
  3. this should open windows file explorer in Appdata\roaming folder
  4. highlight the Thunderbird folder and copy to external media

RESTORE

  1. ensure thunderbird is installed, run once, and NOT running on new PC
  2. enter %appdata% in search window on task bar and press Enter key
  3. delete the thunderbird folder
  4. you should be in Appdata\roaming folder , paste the exported Thunderbird folder there.
  5. start thunderbird and all should be there
MazdaKen
MazdaKen Ki laajte

I am copying from: 

   C:\Users\Ken\AppData\Roaming\Thunderbird

The paste function from the copy buffer is to a portable external harddrive, "J:/Thunderbird-11-Nov-2026", and includes the following folders and files from the Win-10 machine: 

   installs.ini   (file)
   profiles.ini  (file)
   Crash Reports  (folder)
   Pending Pings   (folder)
   Profiles   (folder)
        k1fx5scw.default                     (default folder)
        5zo1yxiu.default-release-1   (folder)
        k1fx5scw.default.old             (folder)
        rpsz3c78.default-release     (folder)
        lhqhc5hj.default                       (folder)

Is there any reason to include any sub-Profiles folder contents other than "k1fx5scw.default" folder contents?

david
david
  • 10 jàppalekat yi jiitu

Everything that thunderbird needs is in the thunderbird folder. everything. actually, more. it only needs to contain the one active profile. over time, thunderbird sometimes has old abandoned profiles, but I wouldn't delete any until you are safely on new PC.

Laajal dara

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.