Software & Apps File Types What Is an XRM-MS File? How to open, edit, & convert XRM-MS files 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 on July 27, 2019 File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More Tweet Share Email A file with the XRM-MS file extension is a Microsoft Security Certificate file. You might also see an XRM-MS file referenced as an XrML Digital License. XRM-MS files are XML files that contain certificate data created by Microsoft and an Original Equipment Manufacturer (OEM) to activate computer software and to digitally verify that the purchase of the software was valid. If you find an XRM-MS file on your Windows computer, such as pkeyconfig.xrm-ms, it's most likely the file with the information about your Windows Activation. You can also find XRM-MS files on a recovery or installation disc that comes with a software purchase. How to Open an XRM-MS File XRM-MS files can be opened with Internet Explorer but they're not really "usable" files. Editing them isn't recommended because it may change the security features of a program, alter its product key, or change permissions of important system data. If you want to see the text content of the XRM-MS file, you can use any text editor to open the file as a text document. The built-in Notepad application in Windows is one option but we often recommend using something a bit more advanced, like one from our Best Free Text Editors list. One example where an XRM-MS file may be something you're working with is if you want to downgrade your Windows version. Sysadmin Lab has an example of this very thing for downgrading from Windows 8 to Windows 7. Always take caution when editing important files that are an integral part of the operation of a software program or operating system. Making an undesired change may not even be noticed at first but could cause serious headaches down the road. If you can't open your XRM-MS file as an XML file, check again that you're not confusing the file extension with one that has a similar extension like an XREF, XLTM, or XLR file, none of which open in the same manner as XRM-MS files. Other programs may utilize the .XRM-MS file extension in their software even if they have nothing at all to do with certificate files. If your XRM-MS file seems to be something else that isn't used in the way described here, try opening it with a free text editor to read the file as a text document. This can sometimes show you text within the file that identifies the program that built it or the type of software that can open it. How to Convert an XRM-MS File XRM-MS files shouldn't be opened, let alone edited, so they definitely should not be converted to another file format. Changing the file extension or attempting to save the XRM-MS file to any other format would most certainly cause issues in any software that's referring to the file. As mentioned above, if you want to see what's in the XRM-MS file, open it and view it. If you must save it to some other text format, you can do it then, but don't expect it to do anything post-conversion.