Delete trainer and all files in
Reboot PC to clear excess memory, get a fresh copy of latest trainer and
make sure trainer is in a folder excluded from virus scans. Empty quarantine folder if needed.
may need to be added to exclusions as well. Run trainer as admin, read the instructions and try again.
Anti-virus help page. Link
Have both latest CORE Link (Both of the Net-Core MUST be installed x86 and x64) and FRAMEWORK Link from Microsoft.
the reason this is happening to you is listed multiple times. Turn off unlimited items or some other option that is on at the same time.
Regarding STEAM users, We do not own the game on steam. I have no idea if there is issues or the game version matches our trainer version. I cannot test the steam version. In the past the EPIC and ROCKSTAR and any other versions all matched and the trainer worked properly.
Make sure your version matches and that you have the lastest trainer if the version matches.
I have no other suggestions.