Today I was running export of an Oracle 18.104.22.168 database. The export completed but with an ORA-600 error:
EXP-00008: ORACLE error 600 encountered ORA-00600: internal error code, arguments: [xsoptloc2], , , , , , ,  ORA-06512: in "SYS.DBMS_AW", line 347 ORA-06512: in "SYS.DBMS_AW", line 470 ORA-06512: in "SYS.DBMS_AW_EXP", line 270 ORA-06512: in line 1 EXP-00083: The previous problem occurred when calling SYS.DBMS_AW_EXP.schema_info_exp
I googled a bit and found that the problem is with applying some patchset. Then metalink confirmed the same. Somebody tried applying a patch to upgrade it to 22.214.171.124 but didn’t perform all the steps (missed post installation steps, to be precise). Metalink Note 300849.1 covers the issue and also gives the solution. In nutshell startup the database with startup migrate and run catpatch.sql.