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

Anuraag Singh | March 6th, 2019 | PDF Updates

PDFs are generally used to store crucial data as an official document. It has become a standard format that is legally accepted in court also. Therefore, users always keep their important information in PDF. Now, it is quite common having multiple PDF files on a local machine that can easily be combined in one. However, when users try to do so, they do not get the desired result. Therefore, why I am unable to combine PDF files is one of the topmost queries searched over the internet. Keeping this necessity of users in mind, we have come up with several methods to merge PDF documents.

“I and my friends are working on one college project. So, every one of us has done his part of work and maintain report in PDF format. Now, to represent all this work as one in college, we need to combine all these PDF files into one report. But, the problem is we are unable to merge PDF files as we don’t know the exact process for the same. If you guys out there know any solution, please suggest.”

Merge Multiple PDF Files into One via Adobe Acrobat

Case #1: PDF is Unsecured

If a user is having an unsecured PDF file, then it is easy for them to combine the documents with the help of Adobe Acrobat. But, what if they want to combine password protected PDF document? Well, the answer to this question is clearly described in this write-up. But, before knowing that, follow these steps to merge unsecured PDF files:

  1. To begin the process, open Adobe Acrobat application on the local machine
  2. After that, click on the Tools menu and choose Combine Files option
  3. Then, you need to click on the Add Files option in order to choose the files that you want to merge in your PDF
  4. Here, you can drag and drop files or pages to reorder them
  5. After that, double-click on a file in order to expand and rearrange all pages
  6. When you are done with arranging of files, click Combine Files button
  7. At last, click on the Save button

Problem: 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 case can be that a user contains multiple PDF files in which some of them are secured with either user-password or owner-password.

In such case, when a user tries to combine password protected PDF files into one via Adobe Acrobat. It asks for the permission password when he/she clicks on the Combine button during the merge PDF process.

If a user does not enter 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 of time, even Adobe Acrobat cannot merge PDF files. So, if a user wants to overcome the situation and wants to merge protected PDF document then simply switch to the third-party solution for the same.

The Professional Way to Combine Password Protected PDF Document

PDF Password Unlock Tool : Software to Unprotect PDF File

If a user is having the restricted PDF document, then it is suggested to remove security first before combining them. Now, the question is how to unsecure the file without knowing the permission password. At this point, a user can take the help of this third-party tool. It is one of the best application to remove security from PDF document. However, it does not ask the user to enter a permission password to unprotect the PDF document. A user just needs to add a secured PDF file, the software will unsecure it without asking for permission password. The application is developed in a way that it removes all restrictions like edit, copy, print, etc. But, if the file is secured with open password then you will be asked to enter it & once the file gets unprotected it becomes password free. Moreover, a user can run this application on any Windows version and does not require Adobe Acrobat program on the machine.

PDF Split & Merge: Tool to Combine PDF Files

As discussed above Adobe Acrobat is unable to combine PDF files if total size exceeds 2 GB limit. To overcome this limitation, a user is suggested to take help of professional solution i.e., PDF Split & Merge tool. 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 PDF without password. Moreover, software does not impose any file size limitation during the merge process. Apart from this, it provides an option to split large size PDF file into multiple parts as per requirement. It is a single tool with multiple functionalities. A user can run this application to merge protected PDF documents on any Windows OS versions.


When it comes to the management of large numbers of PDF files, merging them together is the smart move. But, why users are unable to combine PDF files is one of the frequent problem faced by many users. Therefore, in this post, we have covered all reasons due to which users cannot merge PDF files. Along with this, an alternative solution is also provided to carry out the process.