Aggressive antivirus software (Avast, McAfee, or even Windows Defender under rare heuristic scans) sometimes flags .rpf files as false positives because they contain packed executables. The antivirus may quarantine or delete x64c.rpf , leaving the game unable to find it.
"You have the file now," the digital voice droned. "But the file takes up space. It requires... resources." X64c.rpf Download
If you are looking for this file, it is usually because of a "corrupt game data" error or a failed mod installation. Official Recovery : The safest way to "download" or fix a missing is to use the Verify Integrity of Game Files Aggressive antivirus software (Avast