I recently upgraded to ArcGIS 10.5.1 and also had my desktop reimaged. In trying to establish a connection in ArcCatalog to an Oracle database I am now getting errors when this used to work.
I get the following error, "Failed to connect to the specified server. Do you want to continue? Underlying DBMS error[ORA-12154: TNS:could not resolve the connect identifier specifiedNo extended error.]
I confirmed with our IT help that the Oracle 32 bit client is installed and the path is set in the system variable. I did find some posts relating that error to the install path of the parentheses in the ProgramFiles (x86) and so I uninstalled and tried installing to the top of the C:drive. Although I'm not 100% its installed at that location because I just see C:Desktop10.5 instead of the ArcGIS folder name but all the files look to be in that folder.
I thought by installing at the C: drive location I would eliminate the parentheses issue but after I restarted I'm still getting that connection error.
The connection used to work prior to installing 10.5.1, I think I had 10.3.x installed prior. Does anyone have any suggestions. IT staff is willing to help but the ESRI/Oracle compatibility isn't the most straightforward on how to diagnose.