The mxf file is the page configuration the platfrom uses for the page configuration. Under normal circumstances when you click a button to open the page the platform should always be able to find the page.
This is likely because some old information is being cached somewhere? Are you using a custom widget that might have a reference to an older page?
You can try the following steps to resolve this:
- Empty your cache in the browser
- Clean the deployment directory, in the modeler this is under the menu item run, on an on-premise server this is done by removing the deployment/model folder
If this doesn't help, can you tell us where this error happens? Is this the Mendix Cloud, your local machine, or any of the on-premises configurations? And when?