We usually use synonyms to point to a base object that we don't own it. Let's see a case.
SQL> conn oe/oe@orclpdb1
SQL> select * from countries;
select * from countries
ERROR at line 1:
ORA-00980: synonym translation is no longer valid
In this case, when we tried to access the base object, we got an error. ORA-00980 means that the synonym that you're trying to use is invalid, furthermore, the base object is not existing.
Let's see what base object that the synonym points to.
SQL> column table_owner format a15;
SQL> column table_name format a15;
SQL> select table_owner, table_name from all_synonyms where owner = 'OE' and synonym_name = 'COUNTRIES';
If the base object is a table, we can check whether the table is existing or not.
SQL> select t.owner, t.table_name from all_synonyms s, all_tables t where s.owner = 'OE' and s.synonym_name = 'COUNTRIES' and s.table_owner = t.owner and s.table_name = t.table_name;
no rows selected
Apparently, it's no longer existing. Next, we can check all tables of HR that we can access.
SQL> select table_name from all_tables where owner = 'HR' order by 1;
6 rows selected.
In this case, the table has been renamed to COUNTRIES_BAK. In most cases, the base object don't exist, which caused the synonym no longer valid.
Here I provide 4 ways to solve ORA-00980.
1. Restore the Base Object
If you need the base object very much, you should ask for the owner or DBA to restore it. After that, the synonym will go valid again.
2. Replace Synonym Translation
You can create or replace the synonym with the same name to point to the new table.
SQL> create or replace synonym countries for hr.countries_bak;
The good thing is that, you don't have to change our PL/SQL or application codes because you just replaced the translation underneath.
3. Recreate a New Synonym
To align with the new name of the base object, you can drop it then create a new synonym.
SQL> drop synonym countries;
SQL> create synonym countries_bak for hr.countries_bak;
That is to say, we use the new synonym instead of the old synonym from now on.
4. Drop the Invalid Synonym
If the base object is no way to restore and the above solutions is not applicable to your case, then the synonym is useless, you can drop it anytime.