The system cannot find the path specified. (0x3) - exit code 3 (0x3)

From BOINC Wiki

This error can happen when a file required isn't on your system. This file can be something that the science application specifies in the stderr.txt output message, but it can also be something you'll never know or find out about.

Scenarios where this occurs:

  1. Videocard drivers are too old and need something new in them, so the solution is to update those drivers.
  2. Videocard drivers are missing or corrupt. Reinstall the videocard drivers.
  3. Your anti virus or other anti malware products are blocking the science application from running in the data directory. Exclude the data directory from being actively scanned by your security package.
  4. The developer has added a required file but forgot to add it in the download.
  5. You have no rights to run BOINC on your system.
  6. You have no rights to read from or write to the BOINC data directory.