Mac Error -43 - What is it, why? Does it matter? How can I eliminate it?

Unless you're using some secret software, please share with us what app this is related to.

Have you visited the developer's website for assistance?

The steps you noted that you have taken obviously don't work for every software error that might crop up.

Are there external drives involved here, or just the internal startup drive?

See if the problem still happens in Safe mode (press and hold the shift key down at startup). It can take much longer to safe boot (5 min) so be patient.

How to use safe mode on your Mac - Apple Support 

Safe mode can very often correct weird software behavior by forcing the OS to do cache clearing and other housekeeping. When you're in safe boot, the machine will not be at its best performance, especially with graphics, but that's expected.

Does the problem persist while in Safe mode?

Exit safe mode by restarting your Mac normally and re-evaluate the issue again.

That -43 is a file not found (or maybe directory not found) error, as was shown in the app’s dialogs. What is triggering this is somewhere within the apps or the plugin, or potentially a macOS corruption of some sort, or a nascent hardware error.

MIKEinMICH wrote:

Ok thanks. So, maybe worth trying an OS reinstall, or are the odds better that its the app's problem? Usually trashing Prefs has resolved most any issue with it.

🤷‍♀️

What’s your app exit plan?

I remember Bias Peak.

Before you try to reinstall the OS, see what happens if you delete the app, restart the Mac and reinstall BP.

Of course, a simple reinstallation of the OS may fix the problem. Make sure you do NOT erase, reformat or otherwise alter the startup drive. Just do an OS reinstall. This will leave all of your user files in place and just refresh the OS.

Of course, please make sure you have backed up your system before you do any of this. It would be a shame if something went sideways and you couldn't recover your stuff.

MIKEinMICH wrote:

Nothing on the market has matched it since the 80s so...that's a tough call.

Might want to work on that exit plan, as some part of this app and its accoutrements is going to fail not on your schedule. These legacy app installs tend to coast for a while, then they tend to get intractable and expensive.

I was trying to delete a folder and it kept showing error -43.

Tried many ways -checking for illegal file name, used disk utility first-aid, reset PRAM, and what finally worked in the end was permanently deleting it (Cmd+option+delete).

It's a pretty generic error.

% macerror -43
Mac OS error -43 (fnfErr): File not found