Duplicati might have deleted files it shouldn't have?

I’m pretty sure I ran with --full-remote-verification=true, which I just learned means it samples 30% of contents from each dblock.

The full list of file edits from that job shows a mix of dblock, dindex, and dlist files:

You deleted duplicati-i366536a1a69844d999b7dbd3fcbd0813.dindex.zip.aes
You deleted duplicati-b34ea4703b21446cf9a1bb4d2f2ab9bae.dblock.zip.aes
You deleted duplicati-i7bb4b4b117ef4638bd98332ad1260dd6.dindex.zip.aes
You deleted duplicati-b85c05a99e2db4da59953fcfc391ff31f.dblock.zip.aes
You added duplicati-ib672a96d3a8d4cae8486dfbcce2314ba.dindex.zip.aes
You added duplicati-b708d307742b64f3d87cb8fe0dbe4e050.dblock.zip.aes
You deleted duplicati-i4cfd38a5205c4a46b3db3b0f40e937fa.dindex.zip.aes
You deleted duplicati-b4fc263a0d4284a5f93f2bdcfdd2bc29f.dblock.zip.aes
You added duplicati-i15ef0b86db22434592e420c75e2e10d9.dindex.zip.aes
You added duplicati-b3b19ca271f584534a4c197dff78940f8.dblock.zip.aes
You deleted duplicati-i01604d36733346418f30e2480bd37b09.dindex.zip.aes
You deleted duplicati-bb3bbbef6034643f0aeaf9ed3e44f88a9.dblock.zip.aes
You deleted duplicati-i140ccc4462434fa597d7a41daf7d938d.dindex.zip.aes
You deleted duplicati-bc1af3d803502412f97ddcf2a2f33da29.dblock.zip.aes
You deleted duplicati-i45e99e2666f340f8855a5c26db5560a4.dindex.zip.aes
You deleted duplicati-bf1c2a9972c82458da8bafac54804a26b.dblock.zip.aes
You added duplicati-i68e82cd3495845bab0b9dd7b9a6e113c.dindex.zip.aes
You added duplicati-b0dbdda2d0b354f4e930b7a898d3bbc0b.dblock.zip.aes
You deleted duplicati-i323de50d024b4802a927dcb86d82eb0e.dindex.zip.aes
You deleted duplicati-b9b127936d7f248f69ddd54af80e32bb0.dblock.zip.aes
You deleted duplicati-iaf7dbdf8bf8b47b28d31257cc973b3e8.dindex.zip.aes
You deleted duplicati-bd2b08753927746e1b46d78dbfede6129.dblock.zip.aes
You deleted duplicati-i229932c280b44969a3072673a5be606e.dindex.zip.aes
You deleted duplicati-bb91cb20c091246f7a54b03209bdc42cb.dblock.zip.aes
You added duplicati-ie3e6e49e858841dcaf31c381c4e960ab.dindex.zip.aes
You added duplicati-bfc9c29391b2a4e08afb2abd171488496.dblock.zip.aes
You deleted duplicati-i07358af52edd4ad4b58c20d0aef67d1e.dindex.zip.aes
You deleted duplicati-ba9cc9a3812ee45a49ccacd59775382e7.dblock.zip.aes
You deleted duplicati-ibccc6674190443a8812fe3c07fda8194.dindex.zip.aes
You deleted duplicati-beaa4333b73ac4b31bfb16b32628bd85b.dblock.zip.aes
You added duplicati-ibf7bb0633a124d3abd2bcc56059c62a6.dindex.zip.aes
You added duplicati-bfea57c3a403b48b9842d0115081415d6.dblock.zip.aes
You deleted duplicati-i5fdadc9d4a954cbab927317e4242e514.dindex.zip.aes
You deleted duplicati-b8822bb389daf4611a0413277d7b58c11.dblock.zip.aes
You added duplicati-ia88c0de13c4c496e87e2f5adb41f6b14.dindex.zip.aes
You added duplicati-b0fef29f1ae9c498b8c34c0de31df5bde.dblock.zip.aes
You deleted duplicati-20210930T190952Z.dlist.zip.aes
You added duplicati-20211010T191127Z.dlist.zip.aes
You added duplicati-i6dfdfd6441a940dcb418e470fbc0e31b.dindex.zip.aes
You added duplicati-b3721569259794fd894d50fea3bf40a7c.dblock.zip.aes

The duplicati stored log from that jobshows the typical stack trace; these are the first few lines, but I can’t understand a word of it and it doesn’t seem to mention any files.

System.Security.Cryptography.CryptographicException: Failed to decrypt data (invalid passphrase?): Message has been altered, do not trust content ---> SharpAESCrypt.SharpAESCrypt+HashMismatchException: Message has been altered, do not trust content
  at SharpAESCrypt.SharpAESCrypt.Read (System.Byte[] buffer, System.Int32 offset, System.Int32 count) [0x00405] in <45c43198e80545aeabaa9b98839b4c7d>:0 
  at Duplicati.Library.Utility.Utility.CopyStream (System.IO.Stream source, System.IO.Stream target, System.Boolean tryRewindSource, System.Byte[] buf) [0x0003d] in <5d5d65b1e6e4427684abed657dc45730>:0 
  at Duplicati.Library.Encryption.EncryptionBase.Decrypt (System.IO.Stream input, System.IO.Stream output) [0x00008] in <c36ef9933c0448c2a3eb2c5c27b6f69b>:0

Duplicati is running on an Ubuntu server and backing up via mounted SMB share. It had previously backed the same share up to a local NAS with no errors, and I don’t recall having any issues with the machine at during that backup. Nothing in the Windows Event log and nothing in syslog on the Ubuntu server other than when the drive was mounted for the backup and unmounted after.

I don’t think I have enough detail or knowledge to file a bug report; there’s a lot here I can’t answer because I don’t know what to save or what’s important. If there’s a debugging switch I can use to save better logs for later analysis I’d be happy to add it.

I run about 30 backup jobs to various destinations and this error pops up about once a month at random. Normally I just wipe the backup destination, delete the database, and start over, but since this is a remote destination and my upload speed is limited, I’m less inclined to do that.

In this case I tried deleting backups versions 0 and 1 from this job - I got some errors but then I deleted and recreated the database and the job appears to have run without errors today. Maybe there’s a command I can use to fully test/verify the entire backup set?