Why the error "Exception has been thrown by the target of an invocation" is received during login?

Environment:

Oracle B2C Service, All supported versions

Issue:

Error received in the CX Console during login:

"An Unknown error has occurred, please contact your administrator." and the details in the error text read, "Exception has been thrown by the target of an invocation"

Resolution:

To remedy this issue, have the agent manually delete the following folder: C:\Users\<USER_NAME>\AppData\Roaming\RightNow_Technologies\<SITE_NAME>\.

Then log into the Oracle B2C Service application.

PLEASE NOTE: If the folder C:\Users\<USER_NAME>\AppData\Roaming\ is not visible in Windows Explorer, please enable viewing of system and hidden files.

If the issue persists, please contact Oracle B2C Service Technical Support via Ask Technical Support.

Cause:

During log in, if presented with the above mentioned error message, it means that the Oracle B2C Service application is not able to access all the necessary files located at:
C:\Users\<USER_NAME>\AppData\Roaming\RightNow_Technologies\<SITE_NAME>\.
The cause can be either a file corruption or an accidentally deletion.