What does overread mean when transcoding an MP3 file to OPUS with FFMPEG?

Some times when I transcode particular MP3 files to OPUS using a command like this:

ffmpeg -i file.mp3 -vn -c:a libopus -b:a 32k -vbr on -compression_level 10 -frame_duration 60 -application voip file.opus

I get many "overread" messages like this (the numbers vary):

[mp3float @ 0x55ff85aae340] overread, skip -6 enddists: -4 -423.6x

What does this mean?

UPDATE: Using "mp3" decoder instead of "mp3float" doesn't help. There seem to be no audible differences between the input and the output in the files I have checked so far.

I had the same issue, and mp3val showed that my input data wasn't broken.

I ended up using FREAC for the MP3 decoding and ffmpeg for the Opus encoding.

This setup, although not very elegant, got rid of any errors.