Troubleshooting

The repository format used by restic is designed to be error resistant. In particular, commands like, for example, backup or prune can be interrupted at any point in time without damaging the repository. You might have to run unlock manually though, but that’s it.

However, a repository might be damaged if some of its files are damaged or lost. This can occur due to hardware failures, accidentally removing files from the repository or bugs in the implementation of restic.

The following steps will help you recover a repository. This guide does not cover all possible types of repository damages. Thus, if the steps do not work for you or you are unsure how to proceed, then ask for help. Please always include the check output discussed in the next section and what steps you’ve taken to repair the repository so far.

  • Forum

  • Our IRC channel #restic on irc.libera.chat

Make sure that you use the latest available restic version. It can contain bugfixes, and improvements to simplify the repair of a repository. It might also contain a fix for your repository problems!

1. Find out what is damaged

The first step is always to check the repository.

$ restic check --read-data

using temporary cache in /tmp/restic-check-cache-1418935501
repository 12345678 opened (version 2, compression level auto)
created new cache in /tmp/restic-check-cache-1418935501
create exclusive lock for repository
load indexes
check all packs
check snapshots, trees and blobs
error for tree 7ef8ebab:
  id 7ef8ebabc59aadda1a237d23ca7abac487b627a9b86508aa0194690446ff71f6 not found in repository
[0:02] 100.00%  7 / 7 snapshots
read all data
[0:05] 100.00%  25 / 25 packs
Fatal: repository contains errors

Note

This will download the whole repository. If retrieving data from the backend is expensive, then omit the --read-data option. Keep a copy of the check output as it might be necessary later on!

If the output contains warnings that the ciphertext verification failed for some blobs in the repository, then please ask for help in the forum or our IRC channel. These errors are often caused by hardware problems which must be investigated and fixed. Otherwise, the backup will be damaged again and again.

Similarly, if a repository is repeatedly damaged, please open an issue on Github as this could indicate a bug somewhere. Please include the check output and additional information that might help locate the problem.

If check detects damaged pack files, it will show instructions on how to repair them using the repair pack command. Use that command instead of the “Repair the index” section in this guide.

2. Backup the repository

Create a full copy of the repository if possible. Or at the very least make a copy of the index and snapshots folders. This will allow you to roll back the repository if the repair procedure fails. If your repository resides in a cloud storage, then you can for example use rclone to make such a copy.

Please disable all regular operations on the repository to prevent unexpected changes. Especially, forget or prune must be disabled as they could remove data unexpectedly.

Warning

If you suspect hardware problems, then you must investigate those first. Otherwise, the repository will soon be damaged again.

Please take the time to understand what the commands described in the following do. If you are unsure, then ask for help in the forum or our IRC channel. Search whether your issue is already known and solved. Please take a look at the forum and Github issues.

3. Repair the index

Note

If the check command tells you to run restic repair pack, then use that command instead. It will repair the damaged pack files and also update the index.

Restic relies on its index to contain correct information about what data is stored in the repository. Thus, the first step to repair a repository is to repair the index:

$ restic repair index

repository a14e5863 opened (version 2, compression level auto)
loading indexes...
getting pack files to read...
removing not found pack file 83ad44f59b05f6bce13376b022ac3194f24ca19e7a74926000b6e316ec6ea5a4
rebuilding index
[0:00] 100.00%  27 / 27 packs processed
deleting obsolete index files
[0:00] 100.00%  3 / 3 files deleted
done

This ensures that no longer existing files are removed from the index. All later steps to repair the repository rely on a correct index. That is, you must always repair the index first!

Please note that it is not recommended to repair the index unless the repository is actually damaged.

4. Run all backups (optional)

With a correct index, the backup command guarantees that newly created snapshots can be restored successfully. It can also heal older snapshots, if the missing data is also contained in the new snapshot.

Therefore, it is recommended to run all your backup tasks again. In some cases, this is enough to fully repair the repository.

5. Remove missing data from snapshots

If your repository is still missing data, then you can use the repair snapshots command to remove all inaccessible data from the snapshots. That is, this will result in a limited amount of data loss. Using the --forget option, the command will automatically remove the original, damaged snapshots.

$ restic repair snapshots --forget

snapshot 6979421e of [/home/user/restic/restic] at 2022-11-02 20:59:18.617503315 +0100 CET by user@host
  file "/restic/internal/fuse/snapshots_dir.go": removed missing content
  file "/restic/internal/restorer/restorer_unix_test.go": removed missing content
  file "/restic/internal/walker/walker.go": removed missing content
saved new snapshot 7b094cea
removed old snapshot 6979421e

modified 1 snapshots

If you did not add the --forget option, then you have to manually delete all modified snapshots using the forget command. In the example above, you’d have to run restic forget 6979421e.

6. Check the repository again

Phew, we’re almost done now. To make sure that the repository has been successfully repaired please run check again.

$ restic check --read-data

using temporary cache in /tmp/restic-check-cache-2569290785
repository a14e5863 opened (version 2, compression level auto)
created new cache in /tmp/restic-check-cache-2569290785
create exclusive lock for repository
load indexes
check all packs
check snapshots, trees and blobs
[0:00] 100.00%  7 / 7 snapshots
read all data
[0:00] 100.00%  25 / 25 packs
no errors were found

If the check command did not complete with no errors were found, then the repository is still damaged. At this point, please ask for help at the forum or our IRC channel #restic on irc.libera.chat.