Classic approval process troubleshooting is diagnosing why a record cannot be submitted, routed to the next person, approved, or shown in pending lists. Most failures come from who can see Submit for Approval, whether any process matches the record, a hierarchical approver field that is blank or inactive, a field update that fails standard validation, or email and user setup for delegated approvers. Use the Approval History related list and approval reports to see status, Mass Transfer Approval Requests to unlock stuck records, and treat Flow Approval Processes as the modern alternative when you need to watch submitted records for bottlenecks.