When installing the Toad for Oracle 12.0.1 patch .msp, the following error is displayed:
"The upgrade patch cannot be installed by the Windows Installer service because the program to be upgraded may be missing..."
Please ensure that you have downloaded the correct .msp file for your version of Toad and bit type i.e.
Toad 12.0 32-bit Base, Professional, Xpert, DB Admin and Suites should use:
Toad 12.0 64-bit Base, Professional, Xpert, DB Admin and Suites should use:
Toad 12.0 32-bit Read Only should use:
Toad 12.0.1 32-bit Read Only Patch
Toad 12.0 64-bit Read Only should use:
Toad 12.0.1 64-bit Read Only Patch
See Article 110546 for full downloads list and instructions.