https://www.windowspro.de/andreas-kroschel/fsmo-rollen-im-ad-schema-uebernehmen

as Domain Admin (not a User with Domain Admin role)

ntdsutil
 
fsmo maintenance: connections
server connections: connect to server j-dc01
Binding to j-dc01 ...
Connected to j-dc01 using credentials of locally logged on user.
server connections: q
fsmo maintenance: seize schema master
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