Quote from Twilio Support:
Our engineering has done the investigation with the file and find this file is significantly malformed as a PDF.
If you open it in Preview in OSX, you'll be able to see what's wrong. Notice the first page contains the text "This is a test" "This is going to be a doc converted to pdf". Scroll down to the second page, you'll notice that the text now appears there. Scroll back up to the first page, and the text has disappeared.
This is an unrecoverable error for Programmable Fax. If we attempted to "fix" the structure, there's no guarantee around the integrity of the produced fax.
There is a blog entry describing what's structurally wrong with the PDF is https://blog.idrsolutions.com/2011/05/u ... explained/
The plugin being used to render the file in the browser is more permissive around poorly structured files
Attached are two sample files that they fail to read:
They were produced with code like: `PdfDocument.MergeFiles(streams)` where source streams were two copies of the same simple docx file that was earlier converted to PDF by Spire too.
Are there any specific workarounds we can do to have merged files that are not "Significantly Malformed"?
We were on Spire.Office 3.4.0, but we've also tried it now with 3.7.0.