This weird error seems to pop up from time to time, found this about it in another forum "it is a decoder bug that is exposed when ..." The files seem to be working fine for me ...
I've read through the thread you're quoting from (for the insatiably curious: it's
here).
The discussion in that thread has nothing to do with the error we're talking about. That's because
(1) your FLAC files do not contain ID3 tags.
(2) the error discussed there was a lost sync -- the problem with your files is an unexpected end of file (EOF): they are truncated. Or perhaps more precisely: the values stored in the headers of the files, stating the length of each file, are wrong.
(3) I suspect the claim that it was a decoder bug is (was) incorrect. The decoder merely indicated the problem present in the file.
(4) the thread is 18 years old. No piece of software used then will be still in the state it was at that time.
Is the truncation a problem?
Yes, it is. But not a fatal one since the actual audio is not affected.
Do these files really work for you?
No, they don't. You are going to notice that as soon as you try to decode them to PCM format ("WAV").
flac.exe can be instructed to decode through errors. That is actually the easiest way of correcting this particular defect, and it is what I've done. The decoder will state that the resulting PCM files are shorter than what the headers of the corrupted FLAC files indicated by a few thousand samples (a fraction of a second). Very likely, no audio will even be missing at all. The problem, I assume, is with the length of the files recorded in the headers. These values are simply wrong.
Re-encoding the PCM files to FLAC then results in flawless compressed files.
If I may ask: which software do you use to split files? Is it Audacity?