Opera blocked by OSX 10.8.5

Currently I am on OSX 10.8.5, I don't want to upgrade for multiple reasons. Yesterday out of the blue, the OS stops running after rebooting the machine and tells me I cannot use Opera anymore unless I update to OSX 10.9 I started by downloading older versions of Opera (Currently on 42, downloaded each version back to 37) and in every download get the same install OS X 10.9 message. Any idea anybody? Thanks for the support. **Note**: Upgrading to a later version of macOS is not an option in this case - please do not suggest this as a solution.