Troubleshooting

Common issues and how to fix them.

No PDF files found

  • Make sure the folder contains files with a .pdf extension
  • Files inside subfolders are not included — only files directly in the selected folder
  • Check that files are not hidden or system files

Merge fails for a specific file

  • The source PDF may be password-protected — remove the password protection first
  • If one file fails, the app reports the error and stops — fix or remove the problem file and retry

Merged output has blank or missing pages

Some PDFs — often ones from older report generators or “print to PDF” tools — have an internal index that only partially describes their own contents. Recent versions of the app automatically detect and repair this before merging, so most of these files now merge correctly.

If a merged file still comes out blank:

  • Make sure you’re on the latest version of the app (check the Microsoft Store for updates)
  • Try opening the source PDF in a viewer and re-saving it (e.g. “Print to PDF” or “Save As”) to produce a clean copy, then merge that instead

Output PDF is in the wrong order

Files merge in alphabetical filename order. To control the sequence, add numeric prefixes:

01_cover.pdf
02_intro.pdf
03_chapter.pdf

Use zero-padded numbers (01, 02) rather than unpadded ones (1, 2) to ensure correct alphabetical sorting. See Merge Order for more detail.

Output file already exists

If Skip if output already exists is checked, the app skips the merge when the output file is already present. Uncheck this option to overwrite it, or rename or move the existing output file first.

Output folder cannot be created

  • Check that you have write permission to the output location
  • Avoid network drives or synced folders (OneDrive, Dropbox) as the output location — use a local path such as Documents\BatchMergePDFs instead

App won’t start or crashes on launch

  • Check that Windows is up to date; the app requires Windows 10 or later
  • Reinstall the app from the Microsoft Store if the issue persists

Still stuck?

Email hello@3thousand30.com or open an issue with the error message and a description of the files you were merging.