the bugzilla ticket you have provided doesn't seem to provide a fix to the issue, does it?

although my error is similar to what is shown in the link you provided, so i have tried to restart neutron but the issue is not resolved.

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root@controller:/etc/neutron# journalctl -u neutron-openvswitch-agent -f
-- Logs begin at Mon 2021-07-05 17:48:05 IST. --
Sep 09 14:08:28 controller ovs-vsctl[20957]: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=5 --id=@manager -- create Manager "target=\"ptcp:6640:127.0.0.1\"" -- add Open_vSwitch . manager_options @manager
Sep 09 14:08:28 controller ovs-vsctl[20957]: ovs|00002|ovsdb_idl|WARN|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID dd5aace9-e7b8-4c78-865e-353df69b6286, was inserted by this transaction.  Second row, with UUID cb7a5e48-4ebc-4de4-9289-36aab899abaa, existed in the database before this transaction and was not modified by the transaction.","error":"constraint violation"}
Sep 09 14:08:28 controller ovs-vsctl[20957]: ovs|00003|db_ctl_base|ERR|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID dd5aace9-e7b8-4c78-865e-353df69b6286, was inserted by this transaction.  Second row, with UUID cb7a5e48-4ebc-4de4-9289-36aab899abaa, existed in the database before this transaction and was not modified by the transaction.","error":"constraint violation"}
Sep 09 14:08:28 controller sudo[20948]: pam_unix(sudo:session): session closed for user root
Sep 09 14:08:28 controller sudo[20960]:  neutron : TTY=unknown ; PWD=/var/lib/neutron ; USER=root ; COMMAND=/usr/bin/neutron-rootwrap /etc/neutron/rootwrap.conf ovs-vsctl --timeout=5 --id=@manager -- create Manager target="ptcp:6640:127.0.0.1" -- add Open_vSwitch . manager_options @manager
Sep 09 14:08:28 controller sudo[20960]: pam_unix(sudo:session): session opened for user root by (uid=0)
Sep 09 14:08:28 controller ovs-vsctl[20963]: ovs|00001|vsctl|INFO|Called as /usr/bin/ovs-vsctl --timeout=5 --id=@manager -- create Manager "target=\"ptcp:6640:127.0.0.1\"" -- add Open_vSwitch . manager_options @manager
Sep 09 14:08:28 controller ovs-vsctl[20963]: ovs|00002|ovsdb_idl|WARN|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID cb7a5e48-4ebc-4de4-9289-36aab899abaa, existed in the database before this transaction and was not modified by the transaction.  Second row, with UUID e43c5cbc-6a91-4384-9acd-6751d6fec9e4, was inserted by this transaction.","error":"constraint violation"}
Sep 09 14:08:28 controller ovs-vsctl[20963]: ovs|00003|db_ctl_base|ERR|transaction error: {"details":"Transaction causes multiple rows in \"Manager\" table to have identical values (\"ptcp:6640:127.0.0.1\") for index on column \"target\".  First row, with UUID cb7a5e48-4ebc-4de4-9289-36aab899abaa, existed in the database before this transaction and was not modified by the transaction.  Second row, with UUID e43c5cbc-6a91-4384-9acd-6751d6fec9e4, was inserted by this transaction.","error":"constraint violation"}
Sep 09 14:08:28 controller sudo[20960]: pam_unix(sudo:session): session closed for user root
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