My friend is attempting to install Everest and is running into this error. He has the game installed on an external hard drive and has played before. What could be causing this issue?
#Missing support by filesystem
hybrid oasis
misty sonnet
it is because they're on an external hard drive, but you can just click OK and things should continue fine
fierce flickerBOT
As of the Everest Core update, Everest tries to create symlinks in order to share these two folders between the vanilla and modded installs of the game:
Saves, to sync save data between vanilla and moddedContent, to avoid making a duplicate of all the game assets and save about 1 GB of storage space
However, creating a symlink requires admin privileges on Windows. Installing Everest will still work if you choose not to give admin privileges, but you won't get the benefits listed above.
Creating the symlink can also fail on external drives that use non-NTFS filesystems (such as some flash drives). Installing Everest 4482 or later will still work on these filesystems, but data will not be shared between vanilla and modded. If this is an issue, moving your Celeste install to the C drive should fix it.