Lead Conversion: Order of execution of triggers
On conversion of Lead following is the order of execution of triggers of Account, Opportunity, Contact and Lead:
1) Account Before Trigger
2) Account After Trigger
3) Opportunity Before Trigger
4) Opportunity After Trigger
5) Contact Before Trigger
6) Contact After Trigger
7) Lead Before Trigger
8) Lead After Trigger
All other processes(validations, workflows,approval process, process builders etc. ) executes as per standard order of execution with these triggers and if any exception occurs throughout this process then the complete transaction is rollback.
Execution of triggers of Account,Opportunity and Contact depends on the settings of lead conversion.