We have a similar problem as this one here: Acrobat XI insists on saving every pdf the 1st time it is opened
We are using Adobe Acrobat DC in our Company. We experience the problem, that Acrobat always wants to save changes to PDF documents when closing, even when we have not done any changes. This happens only to more complex PDF files created by CorelDRAW. We already contacted Corel regarding this issue and they said, that the problem is on Adobe side.
We are not using any plugins. The problem exists on all computers when opening files with Acrobat DC. The reader doesnt have this problem.
Thank you in advance
I'll quote from my answer to the question you linked to:
This is an indication for a corrupt PDF file - one that Acrobat can actually fix when it's opening the file. Because the file got fixed when you opened it, it is technically modified (even though you did not modify it via the user interface), and that's why Acrobat prompts you to save the file. Complain to whoever creates these corrupt PDF documents.
This still applies here. Even though Corel claims it's not their problem, if it happens to files only from their product, it is their problem. If you can provide a sample file, we might be able to tell you exactly what's wrong with it.
On behalf of Adobe Systems Incorporated, I'll confirm Karl's response.
Acrobat and Reader are fairly liberal in terms of remediating problematic PDF files and allowing them to be displayed, printed, and otherwise processed. In some cases, significant changes to the original files are necessary such that to prevent future inability to open such files, Acrobat offers to save the “fixed” file.