We've been able to reproduce the problem. It appears to happen when:
If this is the case, a workaround to fix the problem is to map the shared folder to an actual drive letter in Windows, instead of accessing it through the \\.psf\... path. Then open the project again from the mapped network drive.
Please let us know if this solves the problem for you.
First convert to 5.1. If you have complex XML mappings remove them from your project, they will block conversion in several cases of us.
When I create a local app on disk I get the same error. How can you explain this. So I create a new project in Modelere 15.0 and it gives me the error mentioned by Herman: Unable to open 'App.mpr'. It does not appear to be a Modeler project file. And this model is created by the Modeler in the same session!
How to reproduce: 1) Start Modeler 15.0 2) ctrl+Shift+N 3) click: change settings 4) click: Enable team server = No 5) click: create app --> Unable to open 'App.mpr'. It does not appear to be a Modeler project file.
I am using windows 8 professional pro 64 bits in parallel 10.2.0 virtualization. Never had this problem before. Opening projects from version 5.14.1 gives the same error. The error is given during the initialize project phase in the create app dialog.
If you could please create a ticket for this (support.mendixcloud.com), and include the failing project, we'll look into it.
Okay, I figured it out. It appears that Parallels and consequently network related paths cause this issue. I can't open anything in the path "\psf\Home\Documents\", but when I copy the project to my C: drive it opens.
So the ingredients for this recipe is 64-bit Modeler, accessing projects on a network mount/share.
I'm using my Mac, running Parallels Windows 8 64-bit but my documents are shared from my Mac's documents.