Akshay Maniyar
Ansys Employee

Can you try resetting APPDATA folder.
Step 1: Close all Workbench sessions
Step 2: Type %appdata% in the search field of Windows
Step 3: Open the folder named Ansys
Step 4: Locate the folder corresponding to your installation, for instance if you are having error with R19.0 installation, then locate the folder named v190 (similarly, locate v191 for R19.1).
Step 5: Rename this folder as v190_old and start a new WB session.
This will create a fresh copy of the v190 folder (which contains WB environment files) and resolve such issues. The procedure is same for different versions of WB so you just need to rename the appropriate folder.
Thanks amaniyar