Was multi-instance support removed between 3.0.162 dev and 3.0.198 dev?

[modifiedcontent]

Several of my sites stopped working. Has this multi-instance support been removed somewhere between v3.0.162 dev and 3.0.198 dev? Is there now another way to achieve the same?

I urgently need to restore my sites. ?

Is it related to this? Setting $config->useFunctionsAPI  to 'false' makes no difference, so I guess not. The mothersite on the older PW version is still accessible with useFunctionsAPI on false or true; trying to access content from sites on newer PW versions produces a nasty 503 Service Unavailable error. 

[modifiedcontent]

Upgrading the secondary site to the same version as the "mothersite" fixed the issue. As explained here: 'Ideally all instances should be running the same exact version of ProcessWire if possible. At minimum, the versions must be close.'