Any SQL in Optimizer gives "invalid SQL statement ORA-00905" error even if it's valid. (4231973)

Any SQL in Optimizer gives "invalid SQL statement ORA-00905" error even if it's valid.

The Optimizer parser is not identifing the text as a valid SQL statement. It give an ORA-00905 error. But yet, the SQL statement is valid and can be executed. There is only a single statement in the window and no additional scripts. 

Corrupted setting file. 

1. Exit Optimizer. 

2. Go to C:\Users\<personal folder>\AppData\Roaming\Quest Software\Quest SQL Optimizer for Oracle

3. Rename the version folder that applies to your version of Optimizer (i.e. SQL Optimizer for Oracle 8.9.1 will have a \8.9.1 folder. Rename this to \8.9.1_OLD). 

Restart Optimizer and test the issue.

This may apply to various versions of SQL Optimizer for Oracle. Note: renaming the files will for Optimizer to regenerate the directory and files with default values on restart. Previously saved settings and work may not be accessible after restart. But the settings and files are still available to be migrated over if necessary. Note migrating over previous settings and files could also carry over the same issue. Restart Optimizer and test for the issue with each file migrated.