The most frequent cause is trying to open a project file in an older version of After Effects than the one it was saved in. While After Effects is generally backwards compatible, it is not always forwards compatible. The Solution Ensure your Creative Cloud app is fully updated.
If the project uses a plugin you don't have installed, After Effects might struggle to define the properties associated with that plugin. How to Fix The most frequent cause is trying to open
If you don't need the effect, delete the missing effect layer and resave the project. Step 3: Purge Memory and Disk Cache The most frequent cause is trying to open
