this is really interesting as incompatibilities like this are almost unheard of on OSX.
does TurboCad install any Spotlight helper plugins i wonder? that seems to be the only place where a program that's not even running might interact with the filesystem in some way.
rob
I can say i definitely don't have TurboCad installed on my Macbook Pro laptop, nor have ever installed TurboCad on my current Macbook Pro Laptop.
I had intended my previous reply to be the last however I thought is worth updating with the final position regarding the issue with our Macs.
Together with campus IT support we found that installing the program TurboCAD Deluxe V11 for Mac had caused some macOS 10.15.3 Catalina incompatibilities but these only showed up with PixInsight when overwriting an existing general graphics format file. No other graphics processing programs on the Mac seemed to be affected.
Removing TurboCAD did not resolve the problem and we were unable to repair whatever the problem was in the OS and had to rebuild from a wiped drive.
We rebuilt the two problem iMac's in our office without TurboCAD and there were no further issues with PixInsight, we tested my personal iMac Pro by rebuilding from scratch and the issue with PixInsight crashing returned as soon as TurboCAD was re-installed.
Further to that position last week I contacted IMSI (TurboCAD) and having received excellent support they sent me a new installer build for TurboCAD V11 and installing it on my newly rebuilt machine found the issue with PixInsight solved.
I am pleased to say that PixInsight and TurboCAD are now peacefully coexisting on the same machine and I can at last get back to work without having to spend a fortune on purchasing or leasing a different CAD package.
In my case the PixInsight crash on overwrite was a machine(s) specific issue to do with another program that was incompatible with macOS Catalina even though it was 64bit and macOS seemingly had no problem running it or complained when installing it.
Interesting to note that in the previous TurboCAD build there were program file entries in the macOS user library but the current build has none that I can find so it seems everything TC related is now in the applications folder.
Reading around the Mac forums it seems there have been a few issues with program incompatibilities when upgrading the macOS to Catalina from an earlier build such as Mojave, High Sierra etc, it seems I was unlucky enough to find one where it impacted PixInsight.
A couple of further POI's:
For those Mac users who rely on Time Machine to backup their Mac's we found that all of our office Macs (4) and my personal Mac would not restore from a Time Machine backup date prior to upgrading from Mojave to Catalina. The files were visible in the backup as blank icons and were not accessible to Catalina, something had changed with file permissions during the OS update.
Luckily we have a secondary on-line server backup for our office machines (Acronis True Image) and were able to do a documents only restore from there but for my own machine I had to rebuild from scratch.
If you use Time Machine check that the archive is fully accessible to pre OS update times.
A second issue we had with one of the office Macs and a couple of our students MacBooks after upgrading the OS to Catalina we saw random kernel panic crashes after waking from sleep, sometimes within a few minutes of waking, sometimes after a program had been in use for some time.
This was found to be a PRAM issue and simply required PRAM to be reset by booting the Mac from power off while simultaneously holding down the Command+Option+P+R keys until the login prompt appears, after that the random kernel panics ceased.
William.
