There was an error generating document. The specified package is invalid. The main part is missing.
This message sometimes shows when generating a letter document (to be sent by email) on the Claim Details page. It indicates something is wrong with the file, such as the file type.
Both a basic Word 2007 (or later) document and a Strict Open XML Document end in the same extension (.DOCX). However, SimplicityCollect requires that the file needs to be saved as the former (Word 2007 or later) to work properly. Re-save the original file and update the existing letter template from Settings > DocGen Templates, then attempt to generate/email a letter document on an account.