ArcGIS Raster Calculator Error 000539

I am getting the error-000539: Error running expression: rcexec(). I've seen that other people have this same issue but I am not sure how to fix mine. I just want to average the values of 10 rasters, which are .tiff files. This code worked in my older version of ArcGIS but I had to update to the recent one and now it fails.

Here is the full error message:

ERROR 000539: Error running expression: rcexec()

Traceback(most recent call last)P

File "", line1, in

File "", line 8, in rcexec

Here is a picture of my raster calculator code.

This calculation is one step in a model since I need to do this many times. Here is a picture of that too if it helps.