I am trying to save the word document after adding a bookmark in it. but after saving, the saved document does not open. I tried a sample test program on that particular document, Here I am attaching it. can you please let me know, why I face the issue. Looks like the problem with taskpane App, which is included in the document. I tried doing .clear on customparts data. but not sure, what exactly is custom parts data and is there any regression for it. please see the attachments for more clarity.