Answer
The 'SSL is not enabled' message can be a red herring — a common actual cause is missing Microsoft Visual C++ Redistributables on the Windows host: OHS on this middleware version needs both the 64-bit Microsoft Visual C++ 2010 Redistributable and a newer Visual C++ Redistributable (2015-2022 covers the requirement on more recent Windows Server versions) installed, since OHS's httpd process depends on DLLs from both. Check whether msvcr100.dll and a corresponding newer msvcr1xx.dll are present in C:\Windows\System32, install whichever Visual C++ Redistributable package is missing, and retry starting the HTTP server — this has resolved the identical symptom across multiple Windows Server versions (2016, 2019) after both routine installs and OS/Update Server changes.