I am unable to use VarAC native radio control in v3.4. I can select my IC-756 Pro III radio, test frequency change and PTT just fine. When I try to Save & Exit the options, I get a message saying VarAC doesn't have write permissions. Obviously, it does - logs and/or received files are written to the proper directories. What am I missing?

BTW, Omni-Rig works fine. I am not sure I see a reason to implement the built-in radio controls.
If VARAC doesn’t have written permission, it could be due to restrictions on your operating system or incorrect folder settings. Checking user permissions and running the software as an administrator might help. When troubleshooting technical issues, I find it useful to take a structured approach, similar to how researchers analyze data in fields like nursing writing services. Detailed notes on your changes can also help identify the root cause faster. Have you tried reinstalling the software or checking for recent updates?
Ok
It has nothing to do with omnirig/CAT.
there is a simple test in the code that shoot out this error.
This test is trying to write a write and delete a temporary file to the "incoming file directory" to make sure VarAC has access to write incoming files.
Usually this is happening if VarAC is trying to access a directory outside of its own dir and the windows permissions does not allow. you can either change permissions or alternatively run VarAC "as administrator".