listen tcp 127.0.0.1:9090: bind: address already in use

not ideal, but better then nothing:

# systemctl | grep listening
dm-event.socket                                                                                       loaded active     listening    Device-mapper event daemon FIFOs
iscsid.socket                                                                                         loaded active     listening    Open-iSCSI iscsid Socket
iscsiuio.socket                                                                                       loaded active     listening    Open-iSCSI iscsiuio Socket
lvm2-lvmpolld.socket                                                                                  loaded active     listening    LVM2 poll daemon socket
systemd-initctl.socket                                                                                loaded active     listening    /dev/initctl Compatibility Named Pipe
systemd-shutdownd.socket                                                                              loaded active     listening    Delayed Shutdown Socket
virtlockd.socket                                                                                      loaded active     listening    Virtual machine lock manager socket
virtlogd.socket                                                                                       loaded active     listening    Virtual machine log manager socket
# 

in my case it was cockpit.socket (not cockpit.service)