Running bootstrap
Executing ""C:\Program Files\MariaDB 10.3\bin\mysqld.exe" --no-defaults --console --innodb-page-size=16384 --bootstrap "--lc-messages-dir=C:/Program Files/MariaDB 10.3/share" --basedir=. --datadir=. --default-storage-engine=myisam --max_allowed_packet=9M  --net-buffer-length=16k"
2018-10-19 15:33:40 0 [Note] C:\Program Files\MariaDB 10.3\bin\mysqld.exe (mysqld 10.3.9-MariaDB) starting as process 12812 ...
2018-10-19 15:33:40 0 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
2018-10-19 15:33:40 0 [Note] InnoDB: Uses event mutexes
2018-10-19 15:33:40 0 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-10-19 15:33:40 0 [Note] InnoDB: Number of pools: 1
2018-10-19 15:33:40 0 [Note] InnoDB: Using SSE2 crc32 instructions
2018-10-19 15:33:40 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2018-10-19 15:33:40 0 [Note] InnoDB: Completed initialization of buffer pool
2018-10-19 15:33:40 0 [Note] InnoDB: 128 out of 128 rollback segments are active.
2018-10-19 15:33:40 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2018-10-19 15:33:40 0 [Note] InnoDB: Setting file '.\ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2018-10-19 15:33:40 0 [Note] InnoDB: File '.\ibtmp1' size is now 12 MB.
2018-10-19 15:33:40 0 [Note] InnoDB: Waiting for purge to start
2018-10-19 15:33:40 0 [Note] InnoDB: 10.3.9 started; log sequence number 1603959; transaction id 9
2018-10-19 15:33:40 0 [Note] InnoDB: Loading buffer pool(s) from C:\Users\mbe\ib_buffer_pool
2018-10-19 15:33:40 0 [Note] Plugin 'FEEDBACK' is disabled.
2018-10-19 15:33:40 0 [Note] InnoDB: Buffer pool(s) load completed at 181019 15:33:40
ERROR: 1049  Unknown database 'mysql'
2018-10-19 15:33:40 0 [ERROR] Aborting

ERROR: Cannot write to mysqld's stdin
FATAL ERROR: database creation failed
https://mariadb.com/kb/en/installation-issues-on-windows contains some help
for solving the most common problems.  If this doesn't help you, please
leave a comment in the Knowledge Base or file a bug report at
https://jira.mariadb.org