As various topics/threads are closed automatically after 30 days I’m unable to post to those.
Obviously many have experienced the ‘failed to read’ error which many have related to using Audacity with files on a network, in the cloud etc. I personally use Dropbox with MP3 files (podcasts), no multi-tracking involved and my ‘projects’ are limited to batch processing ie applying a palette to multiple files to delete silences for time compression purposes.
This was occurring on both Mac and Windows versions of 3.50 & 3.51 so to experiment I uninstalled and cleaned up traces of Audacity and installed 3.3.3 on both operating systems. Happily the errors have vanished despite all other processes/variables remaining the same (directories, tasks, network etc).
There was minor improvement in file processing speed (truncate silent, export audio) in 3.5x but obviously the error negates any advantage there.
So…depending on your needs, tasks etc. you might try downgrading in version for at least an A/B comparison or to use until such time as the problem is corrected in a new version.
Edit/addendum: the ‘failed to read’ error also occurred (but not always) when a file of 0 length was involved (in, for example, an audio file where all content was deleted but the file was saved and remained). 0-length files no longer cause the error in 3.3.3.