Homebrew MariaDB Server Start Error with 'mysql.server start'
I can reproduce your issue. Don't use mysql.server start in macOS.

If you installed MariaDB with homebrew, use brew services to start and stop the database. It takes only a second and doesn't write strange error to stdout.

brew services stop mariadb
Stopping `mariadb`... (might take a while)
==&gt; Successfully stopped `mariadb` (label: homebrew.mxcl.mariadb)

brew services start mariadb
==&gt; Successfully started `mariadb` (label: homebrew.mxcl.mariadb)


overview of services in homebrew:

brew services list
Name     Status  User     Plist
logstash stopped
mariadb  started Kim /Users/Kim/Library/LaunchAgents/homebrew.mxcl.mariadb.plist
mysql    stopped


general help

brew services --help
brew services command:
    Integrates Homebrew formulae with macOS' launchctl manager.

    [sudo] brew services list
    List all running services for the current user (or root)

    [sudo] brew services run formula|--all
    Run the service formula without starting at login (or boot).

    [sudo] brew services start formula|--all
    Start the service formula immediately and register it to launch at login (or boot).

    [sudo] brew services stop formula|--all
    Stop the service formula immediately and unregister it from launching at login (or boot).

    [sudo] brew services restart formula|--all
    Stop (if necessary) and start the service immediately and register it to launch at login (or boot).

    [sudo] brew services cleanup
    Remove all unused services.

    If sudo is passed, operate on /Library/LaunchDaemons (started at boot).
    Otherwise, operate on ~/Library/LaunchAgents (started at login).