This is the error message I get when I open AE. After Effects error: creating resource file "C:\Program Files\Adobe\Common\Plug-ins\7.0\MediaCore\MisterHorse\AnimationComposer3\AnimationComposer3.aex"
What can I do with it? Today I suddenly got this error after 2 months of use.
Start by checking for an updated version of the plug-in and its associated scripts and install them. Otherwise, even if there is no newer version, reinstall everything. Also delete the AE prefs to get rid of any "tainted" configuration data.