Hi, I have 2 Dovecot servers (2.2.10) which are replicating each other. Replication works fine except for one user. [root at dovecot2 ~]# doveadm -D sync -u username dovecot1 doveadm(root): Debug: Loading modules from directory: /usr/lib64/dovecot doveadm(root): Debug: Module loaded: /usr/lib64/dovecot/lib15_notify_plugin.so doveadm(root): Debug: Module loaded: /usr/lib64/dovecot/lib20_replication_plugin.so doveadm(root): Debug: Loading modules from directory: /usr/lib64/dovecot/doveadm doveadm(root): Debug: Skipping module doveadm_acl_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib10_doveadm_acl_plugin.so: undefined symbol: acl_user_module (this is usually intentional, so just ignore this message) doveadm(root): Debug: Skipping module doveadm_expire_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib10_doveadm_expire_plugin.so: undefined symbol: expire_set_lookup (this is usually intentional, so just ignore this message) doveadm(root): Debug: Skipping module doveadm_quota_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib10_doveadm_quota_plugin.so: undefined symbol: quota_user_module (this is usually intentional, so just ignore this message) doveadm(root): Debug: Module loaded: /usr/lib64/dovecot/doveadm/lib10_doveadm_sieve_plugin.so doveadm(root): Debug: Skipping module doveadm_fts_plugin, because dlopen() failed: /usr/lib64/dovecot/doveadm/lib20_doveadm_fts_plugin.so: undefined symbol: fts_list_backend (this is usually intentional, so just ignore this message) doveadm(username): Debug: Effective uid=489, gid=489, home=/data/mail/username doveadm(username): Debug: fs: root=/data/mail/username, index=, indexpvt=, control=, inbox=, altdoveadm(username): Debug: Namespace : Using permissions from /data/mail/username: mode=0700 gid=default dsync-local(username): Debug: brain M: in state=master_recv_handshake dsync-local(username): Debug: brain M: out state=send_mailbox_tree changed=1 dsync-local(username): Debug: brain M: in state=send_mailbox_tree dsync-local(username): Debug: brain M: out state=send_mailbox_tree_deletes changed=1 dsync-local(username): Debug: brain M: in state=send_mailbox_tree_deletes dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=1 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree dsync-local(username): Debug: brain M: out state=recv_mailbox_tree_deletes changed=1 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree_deletes dsync-local(username): Debug: brain M: out state=recv_mailbox_tree_deletes changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree_deletes dsync-local(username): Debug: brain M: out state=recv_mailbox_tree_deletes changed=0 dsync-local(username): Debug: brain M: in state=recv_mailbox_tree_deletes ...and it hangs. Both servers are CentOS 6.6 x64. Replication status for the problematic user: [root at deoveadm2 ~]# doveadm replicator status username username priority fast sync full sync failed username low 42:10:59 42:10:59 y I tried to reindex the problematic mailbox, tried to restart both mail servers but the issue still here. I found no error messages in /var/log/maillog. What should I try next? Thanks, Laszlo