“Error: Device not supported.” “Error: Compiler XC8 version mismatch.”

The primary reason version 5.35 remains highly sought after is that it is the final version to support the MPASM assembler

Versions up to 5.40 may require a patch to run on macOS 10.15 Catalina or later due to the removal of 32-bit support. Social Media Post Idea

On Windows, right-click the .exe and select "Run as Administrator."

Since Microchip removed old versions from their official downloads page, note these alternative sources:

Newer versions of MPLAB X sometimes drop support for older debuggers. v5.35 retains full support.