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Why Users are Unable to Combine PDF Files: Get Your Answer Here!

Anuraag Singh | Modified: September 21, 2022|PDF Updates | 4 Minutes Reading

PDFs are generally used to store crucial data as an official documents. It has become a standard format that is legally accepted in court also. Therefore, users always keep their important information in PDF. Sometimes users might want to combine or merge their PDF files for better management. But, sometimes they may encounter problems and search for queries like –  why I am unable to combine PDF files, error combining PDF files, there was an error encountered while combining files, Adobe acrobat combine files not working etc, how to combine password protected PDF?

Don’t worry anymore! We got the perfect solution for you but first what can be the issues that cause this scenario.

Why There was an Error Encountered While Combining Files

Case 1: PDF Files Size Issue

While following this method to combine multiple PDF files, if the total size of the resultant PDF file reaches or exceeds 2 GB then the user will be unable to combine PDF files. Moreover, the error message gets displayed on the screen as you try to save the file:

Case 2: PDF is Secured

Another possible cause can be that a user contains multiple PDF files in which some of which are secured with either user-password or owner-password.

In such a case, when a user tries to combine password-protected PDF files into one via Adobe Acrobat. It asks for the permission password.

If a user does not enter a permission password to unlock them, they will be unable to combine PDF files & the Adobe Acrobat will display the following error message:

At that point in time, even Adobe Acrobat cannot combine files. So, if a user wants to overcome the situation and wants to combine password protected PDF documents then simply EITHER switch to the third-party solution to remove security from secured PDF OR use a certain PDF combiner tool that has the in-built facility to unlock files.

Error Combining PDF Files? Get The Best Solution Here!

Solution: PDF Split & Merge Tool by SysTools

 Users are suggested to take the help of a professional solution. A user can run this application to combine password protected PDF documents on any Windows OS and Mac OS versions. This tool is designed in a manner that combines any number of PDF files into one. Also, after removing security from the document users can easily combine password-protected PDFs without passwords. Moreover, the software does not impose any file size limitations during the combining process. Apart from this, it provides an option to split large size PDF files into multiple parts as per requirement. It is a single tool with multiple functionalities. 

For Windows

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For Mac

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How to Combine PDF Files Secured By User-level & Owner-level Security

After downloading and installing the software on your Windows or Mac system, follow the below steps to combine password protected PDF:

Step-1: Click on the “Merge” option given in the tool.

add protected pdfs

Step-2: Click on either “Add File(s)” or “Add Folder” to browse for PDF files. Hit “Next”. One thing you need to keep in mind is that, if your PDFs are protected by a permission password then, no need to enter the password as the tool has the capability to process owner-protected PDFs without needing a password.

Step-3: You can choose to merge options as per your requirement. You can choose to Create a New PDF (after merging) or Merge in the Existing PDF.

Step-4: Hit the Merge button.


When it comes to the management of large numbers of PDF files, combining them together is the smart move. But, why users are unable to combine PDF files is one of the frequent problems faced by many users. Therefore, in this post, we have covered all reasons due to why users can’t combine PDF files. Along with this, an alternative solution is also provided to combine password protected PDF.