The main governor limits that may be in conflict include.
Governor Limits
- Total heap size
- Maximum CPU time on the Salesforce servers
Subquery Limitations
If the template contains Long Text Area/Rich Text Area merge fields of the child object, the maximum number of child records is approximately 50-200 records.
Examples of Violation of Limitations
- Template file size exceeds 1 MB.
- Template contains high quality images.
- Template or record value contains a large number of characters (the number of characters includes the XML tags that consist the file).
- Child records contain Long Text Area merge fields and output more than 50 child records.
Instruction manual