Software & Apps File Types What Is a CBU File? How to open, edit, & convert CBU files Share Pin Email Print File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated February 21, 2019 A file with the CBU file extension is a Comodo Backup file that's created with and used by the free backup program called Comodo Backup. When a backup is made in Comodo Backup, one option is to save the information in a CBU file so that it can be opened again in the future in order to restore those files. The CBU file may hold files, folders, registry data, email information, IM conversations, web browser data, or even entire hard drives or partitions. Some CBU files may instead be Conlab Update Information files, but I don't have any information on what they're used for or what program is needed to open one. How to Open a CBU File CBU files need to be opened with Comodo Backup. The program also lets you build backups in the ZIP or ISO formats. To open a CBU file in Comodo Backup should be as easy as double-clicking the file. However, if that doesn't work, you should first open the program and then go into the Restore section. From there, you can browse for the CBU file from the My Computer, Network, or FTP Server tab. If you've just recently backed up your files to the CBU format, you should see it listed in the Recent Backups section of the Restore tab. That way, you don't have to browse for the file manually. Once you've opened the CBU file in Comodo Backup, you'll be asked what you want to restore out of the backup and where you want to restore it. To restore everything, just make sure the first checkbox is checked so that everything inside it will be restored. Otherwise, click the small plus sign next to the folder to expand it, and then select each individual subfolder and file that you want to be restored, and uncheck the ones you don't want to restore. Once everything you want to restore has a check by it, you can choose a custom folder to restore the files to or you can let Comodo Backup restore everything to the default folder, which is shown toward the bottom of the screen if Restore to default location is checked. Just hit Restore Now to finish the restore. You can also mount a CBU file as a virtual hard drive in Windows so that it shows up in Windows Explorer along with the C drive and other hard drives that are connected to your computer. It might be easier to restore files this way since it's a bit more familiar than using Comodo Backup. This can be done through the Manage > Mounted Drives menu. If you find that an application on your PC does try to open the CBU file but it's the wrong application or if you would rather have another installed program open CBU files, see our How to Change the Default Program for a Specific File Extension guide for making that change in Windows. How to Convert a CBU File Comodo Backup is the program required for opening CBU files, but there isn't an option to convert one to a different format. The CBU file needs to remain in the format it's in, anyway, or Comodo Backup won't know how to open the file, which means you could potentially lose the files you've backed up if you try to convert it with a file conversion tool. However, you can, in a way, "convert" the CBU file to another backup type in Comodo Backup by extracting the files from the CBU file and then putting those files in a different format, such as an ISO or ZIP archive. This isn't really a conversion but it does provide a way to put the same contents from the CBU file into a different file format, which is basically the manual form of what a conversion tool does automatically. Still Can't Open the File? A CBU file that doesn't open with Comodo Backup probably isn't really a CBU file. In other words, you're probably misreading the file extension and confusing another suffix for one that reads ".CBU." This is common when the file extensions look similar. For example, CBR, CBZ, CBT, CB7, and CBA all look very much like they say CBU, but none of those file extensions are used with Comodo Backup, so trying to open one in this backup program will not work and will probably show an error message. Instead, those file formats specifically, while spelled like CBU, are actually CDisplay Archived Comic Book files, and therefore open differently.