Microsoft entra connector on local server fails to connect with event id 12015. The firewalls are all open to allow ports and urls from the server

hi James, thanks for posting this Q,

first off, even if the firewall rules seem correct, event id 12015 usually points to a network or permission issue. the green tick in azure can be misleading sometimes, yeah? it just means the service is running, not necessarily that its communicating properly. Go to the server and check the 'application and services logs' > 'microsoft' > 'entra connector' in event viewer. look for more details around that 12015 error. often it’s a tls issue or the connector can’t reach the required endpoints.

make sure the server has the latest root certificates. sometimes old certs break the handshake. u can download them here https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-install-prerequisites. also, verify the exact urls the connector needs. list of them https://docs.microsoft.com/en-us/azure/active-directory/hybrid/reference-connect-ports.

if u’re using a proxy, the connector might not be configured to use it. check the proxy settings in the connector config file. its usually in 'program files' > 'microsoft entra connector' > 'entraconnector.exe.config'. look for <defaultproxy> tags and adjust if needed.

general tips that might help this could be a dns thing too )) try pinging the entra endpoints from the server. if they time out, u might have a dns resolution problem. also, worth running a quick 'telnet endpoint.com 443' to see if the port is truly open. firewalls can lie sometimes, aha?

as well check this in other tools... if u have any monitoring software like wireshark, capture the traffic. it might show where the connection drops. and yes, restarting the entra connector service never hurts ))

hope this gets u unstuck! if not, hit me with more details...

rgds,

Alex