Problem
This problem occurs if the FTR indexing task fails with an access violation error. This might be because the SPFUsers group does not have permissions on FTR related folders.
Solution
This problem can be solved by reading the FTR environment variables FULCREATE, FULSEARCH, and FULTEMP to get the paths for the FTR related folders. Manually grant personalized permissions (Read, Write, and so on) to the SPFUsers group for FTR related folders.