Oracle Error Message
ORA-01640: cannot make tablespace read-only with changes by in-doubt transactions
Reason for the Error
An attempt was made to alter a tablespace read-only while there were changes in the tablespace made by in-doubt distributed transactions. The in-doubt transactions must commit or rollback to ensure that there is no undo for a tablespace before it can be made read-only.
Solution
Any in-doubt transactions that made changes to the tablespace must be resolved.