1. ORA-00904: Invalid identifier

• This error occurs when a column name specified in a SQL statement is invalid or misspelled. To resolve this issue, double-check the column name in the statement and ensure it matches the actual column name in the database.

2. ORA-12154: TNS:could not resolve the connect identifier specified

• This error indicates that Oracle cannot connect to the specified database service. To fix this, check the TNS entry in the tnsnames.ora file, ensure the database service is running, and verify the network connectivity.

3. ORA-01017: Invalid username/password

• This error occurs when the username or password provided in the connection string is incorrect. Check and verify the username and password, and ensure it is correctly formatted in the connection string.

4. ORA-02291: Integrity constraint violation

• This error indicates a violation of referential integrity constraints when inserting or updating data. To resolve this issue, ensure that the foreign key values match the primary key values in the referenced table.

5. ORA-01555: Snapshot too old

• This error occurs when a query is trying to access data that has been overwritten in the undo tablespace. To resolve this issue, increase the size of the undo tablespace or adjust the query to retrieve a more recent snapshot of the data.

6. ORA-12801: Error signaled in parallel query server

• This error occurs when a parallel query operation encounters an issue. To resolve this, check the parallel query settings, adjust the degree of parallelism, or optimize the query to improve performance.

7. ORA-00600: Internal error

• This error indicates a critical internal error in the Oracle database. It is recommended to contact Oracle Support for assistance in resolving this issue.

8. ORA-01000: Maximum open cursors exceeded

• This error occurs when the maximum number of open cursors allowed in a session is exceeded. To fix this, close unused cursors or increase the open_cursor parameter in the Oracle initialization file.

9. ORA-01722: Invalid number

• This error occurs when a character data is being converted to a number, but the conversion fails. To resolve this, ensure that the data being converted is numeric and formatted correctly.

10. ORA-06502: PL/SQL: numeric or value error

• This error occurs when a numeric or value error is encountered in a PL/SQL block. Check the data being processed and adjust the code to handle the error appropriately.