Can you help me with 2 issues please?
1. I need to combine 2 PDF Files as 1 but I cannot.
2. When I open a PDF File it comes up as Internal Error and I have then to open with Adobe 9.
Could you please confirm whether you are using Acrobat software or accessing Adobe CreatePDF online service to combine files.
If you are online, then you might first need to sign in at "https://cloud.acrobat.com/" using your Adobe ID credentials.
Then, choose 'Combine Files' tab and select appropriate files that you wish to combine as one.
Note: You cannot combine PDFs that are password protected, secure, 3D or part of a PDF portfolio.
Are you able to follow these steps successfully?
Please check for the same and then let me know.