Problem:

When trying to restore a Merge, the restore fails. Sometimes an error message is shown:

“C0001431 - plauti-Too many DML statements: xxx”

Where xxx is a number of 100 or up.

Answer:

When undoing a merge, sometimes a large number of related records needs to be restored, for example because the merged records contained many related records such as contacts, tasks, activities etc in total. In these situations the process to restore the related records can exceed the Salesforce DML Statements limit. 

When the DML Statements limit (total number of related records) is reached, the restore action cannot be processed at all and will fail. Usually this occurs at around 100 related records or more.