Fatal download_chunk

The post on “fixing missing chunks” says:

If you are uninterested in figuring out why the chunk went missing and just want to fix the issue, you can keep removing by hand the affected snapshot files under the snapshots folder in the storage, until the check -a command passes without reporting missing chunks.

So I will try to delete snapshot files in my B2 storage to fix the problem.

The error is:

2020-06-29 12:23:01.113 INFO SNAPSHOT_CHECK All chunks referenced by snapshot DESKTOP-R63ACG7-FC-E at revision 1 exist
2020-06-29 12:23:01.324 FATAL DOWNLOAD_CHUNK Chunk e7b87a8f4d40305923508bf6b2e8e3ab9425f1de9f8cced85bf89e69a3c0dd11 can’t be found
Chunk e7b87a8f4d40305923508bf6b2e8e3ab9425f1de9f8cced85bf89e69a3c0dd11 can’t be found

Question 1: Does this mean that the missing chunk is part of the snapshot “DESKTOP-R63ACG7-FC-E”? Is this the snapshot I should delete? The error message about the missing chunk is on a separate line in the log and doesn’t specifically indicate which snapshot it is related to.

Question 2: In the “(B2 cloud storage)/snapshots/DESKTOP-R63ACG7-FC-E”, all the files have names that are one or two-digit numbers, but file "8 "looks different. It shows a 2 in parenthesis and when clicked, it shows two versions of the file
8 (2)     8K      05/17/2018 00:01
     8      4K      05/17/2018 00:01
     8      4K      05/17/2018 00:01
Why is this? Is the missing chunk problem related, or is this normal?

Question 3: When I search all the files in my local snapshots cache, the chunk hash is not found inside any of those snapshot files. If the chunk does not show up in any of the snapshots files, then how would deleting snapshot files in the cloud resolve the problem?

It is the revision after revision 1 that references a missing chunk.

This can happen if you run two backups with the same snapshot id (DESKTOP-R63ACG7-FC-E) at the same time. Can you check if these 2 versions are the same?

Try deleting the local cache .duplicacy\cache\ first. If you’re running the web GUI the local cache for check/prune is .duplicacy-web\repositories\localhost\all\.duplicacy\cache.

This can happen if you run two backups with the same snapshot id ( DESKTOP-R63ACG7-FC-E ) at the same time. Can you check if these 2 versions are the same?

The two versions are not the same. They are encrypted online, so I cannot see what the difference is. The local cache only has one of them, but I do not know which one.

Try deleting the local cache .duplicacy\cache\ first. If you’re running the web GUI the local cache for check/prune is .duplicacy-web\repositories\localhost\all\.duplicacy\cache.

I deleted the local cache and ran another “check”.
The cache was rebuilt.
The same error came up.

If revision 8 is the revision right after revision 1, it is worth a try to revive the older version of the revision file 8 (by downloading it from the b2 web page and then uploading it again). Clear the local cache and run the check again.

If there is another revision between 1 and 8, then it is this revision that has missing chunks and it is unrelated to revision 8, so what you can do is to manually remove the revision file and run duplicacy prune -exclusive -exhaustive to delete unreferenced chunks.