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I did transfer files from FileZilla Server, using FileZilla 3.55.0 on another PC. Four of the items were multi-GB ISO files. All four of these failed the checksum verification. The files all transferred using TLS 1.3, so, they should be integrity-protected. Data type was Auto and ISO was NOT on the list of files to transfer as ASCII. The strangest thing: No error was mentioned and all marked as successful.

Currently I'm trying to find out what's going on. The target files are always a few KBs bigger.


When I switched to FileZilla Server 0.9.60.2, all files transferred perfectly every time.

Analyzing the nature of corruption.

In fact, the files are not corrupted at all, but the transfer adds 81920 (exactly 80KiB) to the very beginning of the file. Cutting that stub with a hex editor leaves the rest of the file bit-identical to the source one.

Next trying a transfer in the opposite direction (uploading towards the server).

That's a weird one. And why specifically 80KiB, such an odd number.

I'm still in tests. What excludes the hardware is:

1. I have tested it to Marrakesh and back.
2. It is only the unwanted addition. Not a single bit is shifted in the rest of the file.
3. FileZilla Server 0.9.60.2 works flawless every time (using it for a long time now).

Suspicions:
1. Buffer clearing issue?
2. TLS 1.3, the only real major change from old FileZilla (feature-wise).
3. TPM 2.0 chip acting up?

It's a buffer clearing issue.

Did you find it or do I have to conduct more tests? It unfortunately seems to be a sporadic problem and not occurring every session. Would have been too easy.

The stub is simply gibberish (probably parts of a file transferred earlier or in parallel, I always use 4 simultaneous transfers).

Please update to rc4.

Will do.

Just a note concerning the SHA512 file, it is probably built automatically and the server source code checksum has the original path not stripped away.

This bloody build system. If it weren't me who created it, I'd blame the one who created it.

The file is definitely created with without absolute paths at some point. I wonder where it is being overwritten.