If you tried to open a MUI file by double-clicking it and it doesn't open, then you're in the right place, reading the right article. The first thing you should know is that this is an expected behaviour. MUI files are not executable files and do not contain any user specific information which can be displayed. There are several types of MUI files and all of them are used either internally for operating system or by the software.
Most frequently MUI files are used by the Windows OS Multilingual User Interface subsystem. MUI file in this case contain text resources used by the Windows OS and translated to a certain language. Such files could only be opened and interpreted by Windows OS together with corresponding executable file. That is why don’t expect to be able to open MUI file by double clicking on it. Also typically it is safe to assume that MUI files do not contain viruses since they contain only translated text (still some viruses can mask itself as MUI files but it is not typical).
MUI files can also contain files related to Myriad Software music editing program. In this case MUI file stores information about musical instruments used by Myriad Software. Such files can only be opened by Myriad software.
You find out what type of file your MUI file is by looking at the file properties. Just right-click on the file icon and select "Properties" or "More Information". On a Windows computer, the file type will appear under "File type"; on a Mac, it will be under "Class".
Also to find out what MUI file you have you can try to open it either in Microsoft Notepad, Notepad++, or in Visual Studio Code. Even though structure of MUI files is typically binary, there are still text data available in the MUI file and you may be able to infer what type of MUI file it is by just scrolling through MUI file and looking for text information.
MUI Quick Info | |
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Multilingual User Interface Format | |
MIME Type | |
not available | |
Opens with | |
Windows with Multilingual User Interface |