.CMP file extension
To open .CMP files on Windows, determine the .CMP subtype: ask the sender what created it, or note the product/workflow it came from (for example a “CustomMenu” file tied to application/vnd.yellowriver-custom-menu).
To open a .CMP file, first identify what program produced it (ask the sender or check the context it came from). Then open it with that application; if it’s a “CustomMenu” .cmp, it is associated with the MIME type application/vnd.yellowriver-custom-menu and is typically consumed by the software/workflow that uses that vendor format.
Last updated: April 29, 2026 · Reviewed by Julian Stricker
Open on your device
Choose your operating system for a dedicated step-by-step opening guide.
How to open .CMP files
Use these platform-specific instructions to open .CMP files safely.
Windows
- Determine the .CMP subtype: ask the sender what created it, or note the product/workflow it came from (for example a “CustomMenu” file tied to application/vnd.yellowriver-custom-menu).
- Right-click the file → Properties → check the file size and origin; then use Open with… and choose the same application that created or expects this .CMP file (often it is imported via that app’s File → Open/Import menu).
- If you still don’t know the producer, try opening a copy in a plain text editor only to see if it contains readable identifiers; if it looks like binary/garbled text, stop and get the correct application rather than trial-and-error.
Mac
- Identify what created the .CMP file (sender/workflow); .CMP is not a single universal format.
- Control-click → Open With… and pick the producing application (or use that application’s Import/Open feature).
- If you cannot identify the source app, open a copy in a text editor only to check for readable headers; otherwise transfer to the environment/device that generated it and open it there.
Linux
- Confirm what produced the .CMP file; the extension is used by multiple formats, so Linux cannot reliably choose a default app.
- From your file manager, use Open With… and select the program that created/expects the file (often via an Import/Open option inside that program).
- If the file came from a managed system (device suite/enterprise app), open it in that same system’s tools rather than trying generic viewers.
iOS
- iOS typically cannot open .CMP directly; use the Files app to share the file to the specific app that created/expects it, or transfer it to a desktop where that software is available.
Android
- Android typically cannot open .CMP directly; share it to the specific companion/creator app if you have it, otherwise transfer the file to a desktop system with the correct software.
Security notes
- .CMP is an ambiguous extension, so treat it as untrusted until you know which application created it; opening it in the wrong tool can trigger parser bugs or unexpected behavior.
- If you received a .CMP via email/download and you cannot verify the producing software or workflow, do not try random “converter” tools; get the correct application name from the sender.
- In server or enterprise environments, ensure .cmp files are served with the intended registered media type application/vnd.yellowriver-custom-menu when appropriate; incorrect content-type handling can lead to misprocessing by clients and middleware.
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Can't open this file?
These are the most common causes and fixes when .CMP files fail to open.
Common reasons
- The file won’t open or shows as an unknown format
- Opened in the wrong app (garbled text or meaningless output)
- File type association keeps choosing the wrong program
Fix steps
- Ask the sender or check the source system/software to identify what generated the .CMP file.
- Open or import it from within that same application (or its companion tools) instead of relying on double-click.
- If it is part of a MIME-typed workflow, confirm whether it is intended as a “CustomMenu” file associated with application/vnd.yellowriver-custom-menu.
OS-specific troubleshooting
What is a .CMP file?
.CMP is a container/“data file” extension rather than a single universal format. Multiple unrelated formats use .cmp, so file contents can vary widely and there is no one app that reliably opens every .cmp file. In at least one standardized context, .cmp is mapped to the IANA-registered vendor media type application/vnd.yellowriver-custom-menu (often described as “CustomMenu”).
Background
The .cmp extension is best treated as “application-specific data.” Practical opening and troubleshooting depends on where you got it: a device/software suite may generate .cmp files as configuration or menu data, while other programs may use .cmp for completely different purposes.
For environments that rely on MIME types (web servers, content delivery, enterprise software), multiple references map .cmp to the registered vendor media type application/vnd.yellowriver-custom-menu. This mapping is listed in IANA’s media type registry and is also repeated in third-party MIME/extension mapping tables.
Because .cmp is ambiguous, the safest workflow is: determine the producing application or workflow first, then open/import it there. If you cannot identify the source, treat it as unknown binary data and avoid “guessing” with random programs that may misinterpret it.
Common MIME types: application/vnd.yellowriver-custom-menu
Further reading
Authoritative resources for more details on the .CMP format.
Common .CMP issues
The file won’t open or shows as an unknown format
Because .CMP is used by multiple unrelated formats, the OS may not know which program to use, or you may be trying the wrong application for that subtype.
- Ask the sender or check the source system/software to identify what generated the .CMP file.
- Open or import it from within that same application (or its companion tools) instead of relying on double-click.
- If it is part of a MIME-typed workflow, confirm whether it is intended as a “CustomMenu” file associated with application/vnd.yellowriver-custom-menu.
Opened in the wrong app (garbled text or meaningless output)
Many .CMP files are not plain text; opening binary data in a text editor or the wrong program will look corrupted even if the file is fine.
- Stop editing/saving the file after opening it in the wrong program (to avoid overwriting).
- Re-open a fresh copy using the application/workflow that created the file (or expects that subtype).
File type association keeps choosing the wrong program
Once you associate .CMP with an app, your OS may repeatedly open it with that app even when future .CMP files are a different subtype.
- On Windows, use Open with… → Choose another app for just this file; avoid setting a global default unless all your .CMP files come from the same source.
- Prefer opening via the producing application’s File → Open/Import to bypass incorrect OS-level associations.
FAQ
Is .CMP the same thing for every file?
No. Multiple formats use .cmp, so you must identify the producing application or subtype. One common mapping in MIME/type tables is application/vnd.yellowriver-custom-menu (“CustomMenu”), but not all .cmp files are that.
What MIME type is associated with .CMP?
In the IANA media type registry and several extension-to-MIME tables, .cmp is mapped to application/vnd.yellowriver-custom-menu.
Can I convert a file by renaming it to .CMP?
No. Renaming only changes the extension label; it does not convert the internal format. Use the export/import features of the software that created the file, if conversion is supported.
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