I have this too now suddenly. But only in the last version. Better said, in the last version ive downloaded. Not sure if it has updated meanwhile.
My way to there was like this:
- bought, installed, updated and activated the product
- found that my Manual download button is missing and already wondered (so at this stage the installer was working).
- started the sim and saw that no COUATL exe is started.
- saw that many contents of the couatl64 folder is missing
- added folder/files to win defender exclusion
- started couatl updater and it updated all my products. This time the folder contents in couatl64 were a lot more
- started the sim again, this time it seemed to work. The GSX Menu appeared right away.
But it actually didnt. I have a lot of issues (missing textures, menu only works once until couatl needs restart, and more) so i tried updating again.
And now im here. With the same issue. The Installer updates for me until Keywest, then its crashing. With the same error. Unhandled exception.
I for myself have no P3D on this PC and never had. I had it on an older PC yes, but not on this one yet.