Geometry is not M-aware

[TRaabis]

Hello All,
I am in desperate need of help.  I have been trying to run Polygon Neighbors on a large data set but I am constantly getting the following error: The geometry is not M-aware.  After reviewing and trying many different suggestions on an archived ESRI forum I am still running into the error.  This tool has worked for me in the past so I'm stumped as to why it is not working now.  Here is a list of the things that I have tried to solve this error - none of which have worked:
- ran multi-part feature to single part feature
- cleaned the data set
- converted the feature class to a shapefile
- converted the shapefile and feature classes to a new shapefile and feature class and disabling the M value in the environment
- clipped the dataset to a smaller size
- tried running the tool in ArcCatalog and ArcMap 10.1 Basic
- rebooted ArcCatalog and ArcMap and my computer

If anyone has any suggestions it would be greatly appreciated.  Thanks in advance.

Teresa

[deleted-user-ThzEYb7TG5Ko]

This is a fairly old thread/ issue, but I just came across the same error when running a model in 10.6. I solved the issue by opening a new mxd and running the model there. I couldn't tell you why, but that also worked! 

[Nicole_Ueberschär]

I had the problem with tabular intersection and keeping the default database fixed it. Not a good solution though...

EDIT: I just realized that my gdb was named with spaces in the name (wasn't me, I got it from a colleague!!!! ;-)) - After sorting this out, the tool runs totally fine.

[KManning]

I don't know why it worked, but I followed Cory's suggestion and the M-aware issue went away.