Forrtl: severe(47): write to READONLY file, unit 22..
Error Message (Crash): forrtl: sever (47): write to READONLY file, unit 22...
Attempting to write to BST file in ESP.
Analysis: User had two versions of ESP installed, one newer than the other (e.g., Version 9.1 and version 9.2.) Both were open and in use with the same process. The BST was open in v9.1 so v9.2 was prevented from writing to the file.