FRM-407530 ORA-06512 after implementing shared APPL_TOP

Recently an instance was upgraded from 11.5.8 to 11.5.10 and shared APPL_TOP was implemented. After the shared appl_top steps, forms wouldn't launch. Every time a form was accessed it would throw up the FRM-40735 ORA-06512 error. If the forms were manually compiled, they would not compile and throw up errors. After a lot of research, it was found that all the forms were calling a CUSTOM binary which was not copied by the merge process of shared APPL_TOP as it was not a part of core Apps. Once this binary was copied, all the forms could be compiled without issues.