Why setting up new galera cluster with mariabackup as sst starts but all other nodes failed with same error?

I did a fresh reinstallation of mariadb-server on all the nodes (I removed using sudo apt purge mariadb-*) I started the first node using sudo galera_new_cluster it went fine and is still running. but other nodes threw this error: ● mariadb.service - MariaDB 10.3.27 database serverLoaded: loaded (/lib/systemd/system/mariadb.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Sat 2020-12-19 20:23:19 IST; 2min 9s ago Docs: man:mysqld(8) Process: 7089 ExecStartPre=/usr/bin/install -m 755 -o mysql -g root -d /var/run/mysqld (code=exited, status=0/SUCCESS)Process: 7090 ExecStartPre=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)Process: 7092 ExecStartPre=/bin/sh -c [ ! -e /usr/bin/galera_recovery ] && VAR= || VAR=\cd /usr/bin/..; /usr/bin/galera_recovery\; [ $? -eq 0 ] && s` Process: 7330 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION (code=exited, status=1/FAILURE)Main PID: 7330 (code=exited, status=1/FAILURE) Status: "MariaDB server is down" Dec 19 20:22:53 phl-pi-3 systemd: Starting MariaDB 10.3.27 database server... Dec 19 20:22:59 phl-pi-3 sh: WSREP: Recovered position 00000000-0000-0000-0000-000000000000:-1 Dec 19 20:22:59 phl-pi-3 mysqld: 2020-12-19 20:22:59 0 [Note] /usr/sbin/mysqld (mysqld 10.3.27-MariaDB-0+deb10u1-log) starting as process 7330 ... Dec 19 20:22:59 phl-pi-3 mysqld: 2020-12-19 20:22:59 0 [Warning] Could not increase number of max_open_files to more than 16384 (request: 32186) Dec 19 20:23:19 phl-pi-3 systemd: mariadb.service: Main process exited, code=exited, status=1/FAILURE Dec 19 20:23:19 phl-pi-3 systemd: mariadb.service: Failed with result 'exit-code'. Dec 19 20:23:19 phl-pi-3 systemd: Failed to start MariaDB 10.3.27 database server.` this is my galera config: [mysqld]#mysql settings binlog_format=ROW default-storage-engine=innodb innodb_autoinc_lock_mode=2 innodb_doublewrite=1 query_cache_size=0query_cache_type=0 bind-address=0.0.0.0 #galera settings wsrep_on=ON wsrep_provider=/usr/lib/galera/libgalera_smm.so wsrep_cluster_name="test_cluster" wsrep_cluster_address=gcomm://192.168.0.15,192.168.0.16,192.168.0.12,10.8.0.6 wsrep_node_address="192.168.0.15" wsrep_sst_method=mariabackup wsrep_sst_donor=192.168.0.16 all other nodes have same galera config except different wsrep_address and dont have wsrep_sst_donor set. And the other server config is as below: $ cat 50-server.cnf # These groups are read by MariaDB server. # Use it for options that only the server (but not clients) should see ## See the examples of server my.cnf files in /usr/share/mysql/ ## this is read by the standalone daemon and embedded servers [server] skip_name_resolve = 1 # this is only for the mysqld standalone daemon [mysqld] transaction_isolation = READ-COMMITTED binlog_format = ROW innodb_large_prefix=on innodb_file_format=barracuda innodb_file_per_table=1 innodb_io_capacity=4000 # * Basic Settings user = mysqlpid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp lc-messages-dir = /usr/share/mysql skip-external-locking bind-address = 0.0.0.0 # * Fine Tuning key_buffer_size = 16 Mmax_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam_recover_options = BACKUP #max_connections = 100 #table_cache = 64 #thread_concurrency = 10 ## * Query Cache Configuration #query_cache_limit = 1M query_cache_type = 1 query_cache_limit = 2M query_cache_min_res_unit = 2k query_cache_size = 64M ## * Logging and Replication ## Error log - should be very few entries. #log_error = /var/log/mysql/error.log server-id = 16 log_bin = mariadb_bin expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = exclude_database_name innodb_buffer_pool_size = 128M innodb_buffer_pool_instances = 1 innodb_flush_log_at_trx_commit = 2 innodb_log_buffer_size = 32M innodb_max_dirty_pages_pct = 90 # For generating SSL certificates you can use for example the GUI tool "tinyca". ## ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem ## Accept only connections using the latest and most secure TLS protocol version. # ..when MariaDB is compiled with OpenSSL: # ssl-cipher=TLSv1.2 # ..when MariaDB is compiled with YaSSL (default in Debian): # ssl=on ## * Character sets## MySQL/MariaDB default is Latin1, but in Debian we rather default to the full # utf8 4-byte character set. See also client.cnf #character-set-server = utf8mb4 collation-server = utf8mb4_general_ci tmp_table_size= 64Mmax_heap_table_size= 64M slow_query_log = 1 slow_query_log_file = /var/log/mysql/slow.log long_query_time = 1 all other nodes have same as above except different server-id