PDF Conversion Issues

Fix Adobe PDF Combine Tool Failing When Merging Multiple Files

Algirdas Jasaitis Oct 23, 2026 869 views

Question details

The user is experiencing upload delays and processing failures when attempting to combine multiple small PDF files using Adobe PDF services.

Fix Adobe PDF Combine Tool Failing When Merging Multiple Files

Product: Adobe PDF Services
Device & OS: not provided
Scenario: Merging multiple small PDF documents into a single combined file online.
Observed behavior: The upload process takes unusually long and ultimately fails across multiple browsers. Occasionally, only one file uploads successfully, and users may see an 'Operation in progress' error.

Before you start

Ensure your internet connection is stable and that your web browser is updated to the latest version before attempting to combine PDF files online.

Solution 1Recommended

Identify and Isolate Problematic PDF Files

Determine if a specific file containing corrupted data or unsupported elements (like scanned pages) is causing the merge failure.

Upload files individually

Open the Adobe PDF Combine tool and upload your PDF files one by one instead of selecting all of them at once.

Monitor the upload process

Observe which specific file causes the upload progress bar to stall or triggers a failure message.

Change the file order

If the first file uploads successfully but the second fails, try replacing the second file with a different document to verify if the original file is the root cause.

Exclude unsupported content

Remove any identified problematic files (especially scanned PDFs or damaged files) and try merging the remaining compatible files.

Identify and Isolate Problematic PDF Files

Solution 2

Troubleshoot Browser and Network Interference

Resolve potential conflicts caused by browser caching or unstable internet connections interrupting the upload.

Professional PDF Merger

Seamlessly Combine Multiple PDFs Offline with WPS Office

Instead of relying on web-based PDF services that may timeout or fail due to browser issues, use the built-in PDF merger in WPS Office. It securely processes your files locally, ensuring faster speeds and reliable results.

1. Launch WPS PDF: Open WPS Office on your computer and click on 'PDF' from the home screen.
2. Access the Merge tool: Navigate to the 'Page' tab or the main PDF toolkit and select the 'Merge PDF' option.
3. Add your documents: Click 'Add Files' and select all the PDF documents you want to combine from your local drive.
4. Merge the files: Arrange the files in your preferred order by dragging them, then click 'Merge' to instantly create your combined PDF.

Merge unlimited PDF files quickly without size restrictions.Fully compatible with all standard PDF formats and Adobe Acrobat files.Process files locally for enhanced security and zero network dropouts.

microsoft office alternative - wps office

Frequently Asked Questions

Why does my PDF combination fail with an 'Operation in progress' error?

This error usually occurs when a previous upload or merge task gets stuck in the background. Refreshing the web page, clearing your browser cache, or clicking the option to cancel the stalled process typically resolves it.

Can scanned PDFs cause merging tools to fail?

Yes, scanned PDFs or files containing complex layers and extremely high-resolution images can exceed the processing memory limits of online merge tools. Flattening or compressing the PDF before merging can help.

Is there a file size limit when combining PDFs online?

Most online PDF services have strict file size or page count limits. Exceeding these limits often results in timeout errors or upload failures. Using desktop software like WPS Office allows you to bypass these online restrictions.

PDF Troubleshooting