Adobe Acrobat refuses to merge PDFs, how can I merge multiple files into one again?

If Acrobat's "Combine Files" feature doesn't work, make sure your app is up to date. Newer versions fixed a known bug that affected that feature.

Next, use File → Combine Files → Add Files and make sure "Save as PDF Portfolio" is not checked. This will make it merge into a single document instead of a portfolio.

It still won't work if it hangs or won't save when the file size is more than 2 GB. Turn off "Fast Web View" (linearization) in Preferences > Documents, restart, and then try joining again.

As a workaround, you can add each PDF to the Combine tool in Acrobat Online or Adobe Document Cloud from your browser. This often gets around bugs on the desktop.

If you’ve faced a similar issue, don’t hesitate to share your story here. You can also file a complaint on Xolvie to help others in the same situation.