CSO file icon

CSO File Extension

CISO Compressed ISO Format

What is CSO file?

A .CSO file is the first type of compression method that was used for compressing the ISO images. It is also known as the Compressed ISO image file, which provides a high level of compression technique to save the memory space. Generally, the CSO file is used to archive the PlayStation Portable games. The CSO disk image file can be compressed up to nine levels, wherein the higher levels of the CSO disk image file depict a greater compression of the ISO image with a lower downloading speed. The CSO file is created by the ISO compressor tools, such as PSP ISO Compressor, YACC to name a few.

Programs which support CSO file extension

The following list contains programs grouped by 3 operating systems that support CSO files. CSO files can be encountered on all system platforms, including mobile, yet there is no guarantee each will properly support such files.

Programs that support CSO file

Updated: 04/24/2023

How to open file with CSO extension?

Being unable to open files with CSO extension can be have various origins. What is important, all common issues related to files with CSO extension can be resolved by the users themselves. The process is quick and doesn’t involve an IT expert. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Install UMDGen software

Install software to open CSO file Problems with opening and working with CSO files are most probably having to do with no proper software compatible with CSO files being present on your machine. The most obvious solution is to download and install UMDGen or one to the listed programs: CisoPlus!, YACC, Yet Another CSO Compressor. 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 UMDGen installer in the most secured manner, we suggest you visit website and download from their official repositories.

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

Update software that support file extension CSOIf you already have UMDGen installed on your systems and CSO files are still not opened properly, check if you have the latest version of the software. It may also happen that software creators by updating their applications add compatibility with other, newer file formats. The reason that UMDGen cannot handle files with CSO may be that the software is outdated. The most recent version of UMDGen is backward compatible and can handle file formats supported by older versions of the software.

Step 3. Assign UMDGen to CSO files

After installing UMDGen (the most recent version) make sure that it is set as the default application to open CSO files. The next step should pose no problems. The procedure is straightforward and largely system-independent

Associate software with CSO file on Windows

Change the default application in Windows

  • Choose the Open with entry from the file menu accessed by right-mouse clicking on the CSO file
  • Click Choose another app and then select More apps option
  • Finally select Look for another app on this PC, point to the folder where UMDGen is installed, check the Always use this app to open CSO files box and conform your selection by clicking OK button
Associate software with CSO file on Mac

Change the default application in Mac OS

  • From the drop-down menu, accessed by clicking the file with CSO extension, select Information
  • Open the Open with section by clicking its name
  • Select UMDGen and click Change for all...
  • Finally, a This change will be applied to all files with CSO extension message should pop-up. Click Continue button in order to confirm your choice.

Step 4. Check the CSO for errors

You closely followed the steps listed in points 1-3, but the problem is still present? You should check whether the file is a proper CSO file. Being unable to access the file can be related to various issues.

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

If the CSO is indeed infected, it is possible that the malware is blocking it from opening. Scan the CSO file as well as your computer for malware or viruses. If the CSO file is indeed infected follow the instructions below.

2. Ensure the file with CSO extension is complete and error-free

Did you receive the CSO file in question from a different person? Ask him/her to send it one more time. During the copy process of the file errors may occurred rendering the file incomplete or corrupted. This could be the source of encountered problems with the file. When downloading the file with CSO extension from the internet an error may occurred resulting in incomplete file. Try downloading the file again.

3. Ensure that you have appropriate access rights

Sometimes in order to access files user need to have administrative privileges. Switch to an account that has required privileges and try opening the CISO Compressed ISO Format file again.

4. Make sure that the system has sufficient resources to run UMDGen

The operating systems may note enough free resources to run the application that support CSO files. Close all running programs and try opening the CSO file.

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

Up-to-date system and drivers not only makes your computer more secure, but also may solve problems with CISO Compressed ISO Format file. It is possible that one of the available system or driver updates may solve the problems with CSO files affecting older versions of given software.

Conversion of a CSO file

File Conversions from CSO extension to a different format
File conversions from other format to CSO file
Do you want to help?

If you have additional information about the CSO 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 CSO file.

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