topic Upgrading to 10.4 -- don't forget to adjust your PYTHON environemnt variables in ArcGIS Desktop Installation Support Questions https://community.esri.com/t5/arcgis-desktop-installation-support-questions/upgrading-to-10-4-don-t-forget-to-adjust-your/m-p/736582#M120 <HTML><HEAD></HEAD><BODY><P>Had an install of ArcGIS 10.4 where ArcMap would just falter and never open.</P><P></P><P>Spent the day with Process Monitor looking for missing Global cache, and then realized that I'd left the PYTHONHOME environment variable set to C:\Python2.7\ArcGIS10.3, and the PYTHONPATH composed from it.</P><P></P><P>Suffice to say that bad things happen with ArcMAP when PYTHONHOME &amp; PYTHONPATH are not reset following an upgrade. <IMG src="https://community.esri.com/legacyfs/online/emoticons/blush.png" /></P><P></P><P>Add it to your upgrade/install check list.</P></BODY></HTML> Wed, 02 Mar 2016 00:03:34 GMT V_StuartFoote 2016-03-02T00:03:34Z Upgrading to 10.4 -- don't forget to adjust your PYTHON environemnt variables https://community.esri.com/t5/arcgis-desktop-installation-support-questions/upgrading-to-10-4-don-t-forget-to-adjust-your/m-p/736582#M120 <HTML><HEAD></HEAD><BODY><P>Had an install of ArcGIS 10.4 where ArcMap would just falter and never open.</P><P></P><P>Spent the day with Process Monitor looking for missing Global cache, and then realized that I'd left the PYTHONHOME environment variable set to C:\Python2.7\ArcGIS10.3, and the PYTHONPATH composed from it.</P><P></P><P>Suffice to say that bad things happen with ArcMAP when PYTHONHOME &amp; PYTHONPATH are not reset following an upgrade. <IMG src="https://community.esri.com/legacyfs/online/emoticons/blush.png" /></P><P></P><P>Add it to your upgrade/install check list.</P></BODY></HTML> Wed, 02 Mar 2016 00:03:34 GMT https://community.esri.com/t5/arcgis-desktop-installation-support-questions/upgrading-to-10-4-don-t-forget-to-adjust-your/m-p/736582#M120 V_StuartFoote 2016-03-02T00:03:34Z