If the quick fixes above don't solve the problem, proceed with these more advanced steps. Some of these will be particularly relevant if you're using a "portable" version or had a trainer installed previously.
When a (pre-installed, no-install) version is used, this file is often either skipped during copying, corrupted during download, or, most commonly, blocked or quarantined by anti-virus software. Causes of the FC_m64.dll Missing Error far cry 5 fcm64dll missing portable
Open > Virus & threat protection > Protection history . If the quick fixes above don't solve the