Model name has been changed to XYZ.erwin.1 and it cannot be opened.

What causes a .1 to be added the file extension of the erwin model. For example, XYZ.erwin was changed to XYZ.erwin.1 and can no longer be opened in erwin. 

Solution:

This type of file rename usually happens when an abnormal termination occurs while you are working with a model. An event that may cause this to occur is when erwin crashes in the middle of a complete compare. This can happen due to some form of corruption within some of the objects in the model. After the crash, you may find that the erwin file is now renamed with a .1 in the back of the extension. This file cannot be opened in erwin, but it can be recovered by simply removing the .1 from the file extension (ie. renaming XYZ.erwin.1 to XYZ.erwin). Before renaming the .1 file, first take a backup of the file and then rename the original and try opening in erwin. If you continue to have issues with the model after recovering it, you can clean the model following the below process or you can contact erwin support and we can assist in cleaning/debugging the model.

How to use Complete Compare to 'clean' problematic models?

https://support.erwin.com/hc/en-us/articles/233414427-How-to-use-Complete-Compare-to-clean-problematic-models-