P21 file icon

P21 File Extension

PAR Recovery Volume

What is P21 file?

P21 files are associated with Parchive system.

What kind of data can P21 files store?

P21 files are so-called parity archives. Data in P21 files is used to reliably send information over a network (Usenet). The problem with sending data over network such as Usenet was the the connection dropped frequently and network infrastructure was unreliable. Parchive standard uses parity volumes files marked with special suffix (letter P and a number, for example P21, where 21 is the parity code) during data recovery, that is to reconstruct the data send over the network if any data is missing due to connection error.

Where is Parchive standard commonly applied?

Parchive is commonly used for securing data stored on disks against malware, data corruption, system or device failures, or accidental deletion. Parity archive files (P2, P1, or others) are used to to recover lost data. Parity archive files can also be use to preserve integrity of data sent over a network.

Programs which support P21 file extension

The following listing features P21-compatible programs. Files with P21 extension, just like any other file formats, can be found on any operating system. The files in question may be transferred to other devices, be it mobile or stationary, yet not all systems may be capable of properly handling such files.

Programs that support P21 file

Windows Windows

Updated: 10/28/2022

How to open file with P21 extension?

Being unable to open files with P21 extension can be have various origins. On the bright side, the most encountered issues pertaining to PAR Recovery Volume files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Install QuickPar software

Install software to open P21 file The main and most frequent cause precluding users form opening P21 files is that no program that can handle P21 files is installed on user’s system. The solution is straightforward, just download and install QuickPar. On the top of the page a list that contains all programs grouped based on operating systems supported can be found. If you want to download QuickPar installer in the most secured manner, we suggest you visit Peter B. Clements website and download from their official repositories.

Step 2. Verify the you have the latest version of QuickPar

Update software that support file extension P21If you already have QuickPar installed on your systems and P21 files are still not opened properly, check if you have the latest version of the software. Software developers may implement support for more modern file formats in updated versions of their products. The reason that QuickPar cannot handle files with P21 may be that the software is outdated. The latest version of QuickPar should support all file formats that where compatible with older versions of the software.

Step 3. Assign QuickPar to P21 files

If the issue has not been solved in the previous step, you should associate P21 files with latest version of QuickPar you have installed on your device. The method is quite simple and varies little across operating systems.

Associate software with P21 file on Windows

Change the default application in Windows

  • Right-click the P21 file and choose Open with option
  • Click Choose another app and then select More apps option
  • The last step is to select Look for another app on this PC option supply the directory path to the folder where QuickPar is installed. Now all that is left is to confirm your choice by selecting Always use this app to open P21 files and clicking OK.
Associate software with P21 file on Mac

Change the default application in Mac OS

  • By clicking right mouse button on the selected P21 file open the file menu and choose Information
  • Find the Open with option – click the title if its hidden
  • Select QuickPar and click Change for all...
  • A message window should appear informing that This change will be applied to all files with P21 extension. By clicking Continue you confirm your selection.

Step 4. Check the P21 for errors

If you followed the instructions form the previous steps yet the issue is still not solved, you should verify the P21 file in question. It is probable that the file is corrupted and thus cannot be accessed.

Check P21 file for viruses
1. The P21 may be infected with malware – make sure to scan it with an antivirus tool.

Should it happed that the P21 is infected with a virus, this may be that cause that prevents you from accessing it. Immediately scan the file using an antivirus tool or scan the whole system to ensure the whole system is safe. If the scanner detected that the P21 file is unsafe, proceed as instructed by the antivirus program to neutralize the threat.

2. Check whether the file is corrupted or damaged

Did you receive the P21 file in question from a different person? Ask him/her to send it one more time. The file might have been copied erroneously and the data lost integrity, which precludes from accessing the file. It could happen the the download process of file with P21 extension was interrupted and the file data is defective. Download the file again from the same source.

3. Verify whether your account has administrative rights

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Switch to an account that has required privileges and try opening the PAR Recovery Volume file again.

4. Check whether your system can handle QuickPar

If the system is under havy load, it may not be able to handle the program that you use to open files with P21 extension. In this case close the other applications.

5. Verify that your operating system and drivers are up to date

Latest versions of programs and drivers may help you solve problems with PAR Recovery Volume files and ensure security of your device and operating system. Outdated drivers or software may have caused the inability to use a peripheral device needed to handle P21 files.

Do you want to help?

If you have additional information about the P21 file, we will be grateful if you share it with our users. To do this, use the form here and send us your information on P21 file.

Top File Extensions
Show more
File Extension of the day
3dxml icon


Dassault Systemes 3D XML Format

3DXML is a lightweight, universal file format based on XML developed by Dassault Systemes for 3DVIA solution for 3D data exchange. Single 3DXML can...

Last updated