diff --git a/cmake/install_layout.cmake b/cmake/install_layout.cmake
index 55e960a3c1572..ecd65b0419a4c 100644
--- a/cmake/install_layout.cmake
+++ b/cmake/install_layout.cmake
@@ -192,7 +192,7 @@ SET(INSTALL_MYSQLTESTDIR_DEB            "share/mariadb/mariadb-test")
 SET(INSTALL_SQLBENCHDIR_DEB             ".")
 SET(INSTALL_SUPPORTFILESDIR_DEB         "share/mariadb")
 #
-SET(INSTALL_MYSQLDATADIR_DEB            "/var/lib/mysql")
+SET(INSTALL_MYSQLDATADIR_DEB            "/var/lib/mariadb")
 
 SET(INSTALL_RUNDATADIR_DEB              "/run/mysqld")
 SET(INSTALL_UNIX_ADDRDIR_DEB            "${INSTALL_RUNDATADIR_DEB}/mysqld.sock")
diff --git a/debian/additions/mariadb.conf.d/50-server.cnf b/debian/additions/mariadb.conf.d/50-server.cnf
index 66301f78e636b..ab17ce3ecd330 100644
--- a/debian/additions/mariadb.conf.d/50-server.cnf
+++ b/debian/additions/mariadb.conf.d/50-server.cnf
@@ -15,7 +15,7 @@
 #user                    = mysql
 pid-file                = /run/mysqld/mysqld.pid
 basedir                 = /usr
-#datadir                 = /var/lib/mysql
+#datadir                 = /var/lib/mariadb  # Starting with MariaDB 1:11.8.6-5, /var/lib/mariadb is used by default for better MySQL co-installability in Debian/Ubuntu.
 #tmpdir                  = /tmp
 
 # Broken reverse DNS slows down connections considerably and name resolve is
diff --git a/debian/additions/source_mariadb.py b/debian/additions/source_mariadb.py
index a91695a704846..5a743fa9c6e9c 100644
--- a/debian/additions/source_mariadb.py
+++ b/debian/additions/source_mariadb.py
@@ -42,6 +42,10 @@ def add_info(report):
         _add_my_conf_files(report, os.path.join('/etc/mysql/conf.d', f))
     for f in os.listdir('/etc/mysql/mariadb.conf.d'):
         _add_my_conf_files(report, os.path.join('/etc/mysql/mariadb.conf.d', f))
+    try:
+        report['MariaDBVarLibDirListing'] = str(os.listdir('/var/lib/mariadb'))
+    except OSError:
+        report['MariaDBVarLibDirListing'] = str(False)
     try:
         report['MySQLVarLibDirListing'] = str(os.listdir('/var/lib/mysql'))
     except OSError:
diff --git a/debian/mariadb-server.mariadb.init b/debian/mariadb-server.mariadb.init
index 765640327d19d..0d8d72dffce7f 100644
--- a/debian/mariadb-server.mariadb.init
+++ b/debian/mariadb-server.mariadb.init
@@ -96,7 +96,7 @@ sanity_checks() {
   # and this should fall back to a sane default value
   if [ -z "$datadir" ]
   then
-    datadir="/var/lib/mysql"
+    datadir="/var/lib/mariadb"
   fi
 
   # Verify the datadir location exists
diff --git a/debian/mariadb-server.postinst b/debian/mariadb-server.postinst
index 3d7ff59bb4a1e..a872d04ff0325 100644
--- a/debian/mariadb-server.postinst
+++ b/debian/mariadb-server.postinst
@@ -61,11 +61,30 @@ case "$1" in
     fi
 
     mariadb_statedir=/usr/share/mariadb
-    mariadb_datadir=/var/lib/mysql
+    mariadb_datadir=/var/lib/mariadb
+    legacy_mariadb_datadir=/var/lib/mysql
     mariadb_logdir=/var/log/mysql
     mariadb_cfgdir=/etc/mysql
     mariadb_upgradedir=/var/lib/mysql-upgrade
 
+    # If new mariadb data directory does not exist, assume we are continuing
+    # to use the legacy directory. Add a config entry to override datadir's
+    # value back to the original.
+    if [ ! -d "$mariadb_datadir" ]
+    then
+      mariadb_datadir="$legacy_mariadb_datadir"
+
+      mkdir -p /etc/mysql/mariadb.conf.d
+
+      {
+        echo "# Override the data directory config to continue using the legacy directory."
+        echo "[mariadbd]"
+        echo "datadir = $legacy_mariadb_datadir"
+      } > /etc/mysql/mariadb.conf.d/99-legacy-datadir.cnf
+
+      echo "Created /etc/mysql/mariadb.conf.d/99-legacy-datadir.cnf for MariaDB to continue using /var/lib/mysql on upgrade."
+    fi
+
     # If the following symlink exists, it is a preserved copy the old data dir
     # created by the preinst script during a upgrade that would have otherwise
     # been replaced by an empty mysql dir.  This should restore it.
@@ -181,12 +200,8 @@ EOF
     # data directory and then somehow gets purged by the admin.
     db_set mariadb-server/postrm_remove_database false || true
 
-    # Clean up old flags before setting new one
+    # Clean up old debian version flag files
     rm -f $mariadb_datadir/debian-*.flag
-    # Flag data dir to avoid downgrades
-    # @TODO: Rewrite this to use the new upstream /var/lib/mysql_upgrade_info file
-    # instead of the legacy /var/lib/debian-XX.X.flag file
-    touch "$mariadb_datadir/debian-__MARIADB_MAJOR_VER__.flag"
 
     # initiate databases. Output is not allowed by debconf :-(
     # This will fail if we are upgrading an existing database; in this case
@@ -198,6 +213,7 @@ EOF
     # working with libpam-tmpdir (by setting TMPDIR to empty value).
     set +e
     TMPDIR='' bash /usr/bin/mariadb-install-db \
+      --datadir="$mariadb_datadir" \
       --rpm --cross-bootstrap \
       --user=mysql --disable-log-bin \
       --skip-test-db 2>&1 | \
diff --git a/debian/mariadb-server.postrm b/debian/mariadb-server.postrm
index 601fe87f7e9ad..9afb8428cdd23 100644
--- a/debian/mariadb-server.postrm
+++ b/debian/mariadb-server.postrm
@@ -12,16 +12,70 @@ fi
 
 ${DEBIAN_SCRIPT_TRACE:+ echo "#42#DEBUG# RUNNING $0 $*" 1>&2 }
 
+mariadb_datadir=/var/lib/mariadb
+legacy_mariadb_datadir=/var/lib/mysql
+
+# Check if the version file mariadb_upgrade_info or mysql_upgrade_info is
+# included with the provided data directory. If it is a MariaDB version, then
+# return the major version number only (XX.XX). Return empty if this directory
+# does not belong to MariaDB.
+get_mariadb_upgrade_info_major_version() {
+  datadir="$1"
+
+  # Check both mariadb_upgrade_info (higher priority) and mysql_upgrade_info.
+  if [ -f "$datadir/mysql_upgrade_info" ]
+  then
+    read -r full_version < "$datadir/mysql_upgrade_info"
+  fi
+
+  if [ -f "$datadir/mariadb_upgrade_info" ]
+  then
+    read -r full_version < "$datadir/mariadb_upgrade_info"
+  fi
+
+  # If version is not empty and contains 'MariaDB', get the version number.
+  if [ -n "$full_version" ] && echo "$full_version" | grep -q "MariaDB"
+  then
+    # The major version number should the first two components of the version
+    # string (e.g. 11.8 from 11.8.6).
+    echo "$full_version" | awk -F'.' '{print $1"."$2}'
+  fi
+}
+
 #
 # - Purge logs and data only if they are ours (#307473)
 # - Remove the mysql user only after all his owned files are purged.
 # - Cleanup the initscripts only if this was the last provider of them
 #
-if [ "$1" = "purge" ] && [ -f "/var/lib/mysql/debian-__MARIADB_MAJOR_VER__.flag" ]
+if [ "$1" = "purge" ]
 then
-  # we remove the mysql user only after all his owned files are purged
-  rm -f /var/log/mysql.{log,err}{,.0,.[1234567].gz}
-  rm -rf /var/log/mysql
+  rm -f /etc/mysql/mariadb.conf.d/99-legacy-datadir.cnf
+
+  # Mark data directories for removal if they match the current MariaDB version.
+  remove_mariadb_datadir="false"
+  remove_legacy_mariadb_datadir="false"
+
+  mariadb_datadir_version=$(get_mariadb_upgrade_info_major_version "$mariadb_datadir")
+
+  if [ "$mariadb_datadir_version" = "__MARIADB_MAJOR_VER__" ]
+  then
+    remove_mariadb_datadir="true"
+  fi
+
+  legacy_mariadb_datadir_version=$(get_mariadb_upgrade_info_major_version "$legacy_mariadb_datadir")
+
+  if [ "$legacy_mariadb_datadir_version" = "__MARIADB_MAJOR_VER__" ]
+  then
+    remove_legacy_mariadb_datadir="true"
+  fi
+
+  # Remove logs in /var/log/mysql only if they are ours.
+  # These must be removed before mysql user is removed.
+  if [ "$remove_mariadb_datadir" = "true" ] || [ "$remove_legacy_mariadb_datadir" = "true" ]
+  then
+    rm -f /var/log/mysql.{log,err}{,.0,.[1234567].gz}
+    rm -rf /var/log/mysql
+  fi
 
   db_input high "mariadb-server/postrm_remove_databases" || true
   db_go || true
@@ -30,26 +84,47 @@ then
   then
     # never remove the debian.cnf when the databases are still existing
     # else we ran into big trouble on the next install!
-    rm -f /etc/mysql/debian.cnf
-    # Remove all contents from /var/lib/mysql except if it's a
+    if [ "$remove_mariadb_datadir" = "true" ] || [ "$remove_legacy_mariadb_datadir" = "true" ]
+    then
+      rm -f /etc/mysql/debian.cnf
+    fi
+    # Remove all contents from /var/lib/mariadb except if it's a
     # directory with file system data. See #829491 for details and
     # #608938 for potential mysql-server leftovers which erroneously
     # had been renamed.
     # Attempt removal only if the directory hasn't already been removed
     # by dpkg to avoid failing on "No such file or directory" errors.
-    if [ -d /var/lib/mysql ]
+    if [ "$remove_mariadb_datadir" = "true" ]
     then
-      find /var/lib/mysql -mindepth 1 \
+      find "$mariadb_datadir" -mindepth 1 \
+        -not -path '*/lost+found/*'     -not -name 'lost+found' \
+        -not -path '*/lost@002bfound/*' -not -name 'lost@002bfound' \
+        -delete
+
+      # "|| true" still needed as rmdir still exits with non-zero if
+      # /var/lib/mariadb is a mount point
+      rmdir --ignore-fail-on-non-empty "$mariadb_datadir" || true
+    fi
+    # Remove all contents from /var/lib/mysql if it's owned by us, with same
+    # checks as /var/lib/mariadb.
+    if [ "$remove_legacy_mariadb_datadir" = "true" ]
+    then
+      find "$legacy_mariadb_datadir" -mindepth 1 \
         -not -path '*/lost+found/*'     -not -name 'lost+found' \
         -not -path '*/lost@002bfound/*' -not -name 'lost@002bfound' \
         -delete
 
       # "|| true" still needed as rmdir still exits with non-zero if
       # /var/lib/mysql is a mount point
-      rmdir --ignore-fail-on-non-empty /var/lib/mysql || true
+      rmdir --ignore-fail-on-non-empty "$legacy_mariadb_datadir" || true
+    fi
+
+    # Remove /run/mysqld and mysql user if owned by us.
+    if [ "$remove_mariadb_datadir" = "true" ] || [ "$remove_legacy_mariadb_datadir" = "true" ]
+    then
+      rm -rf /run/mysqld # this directory is created by the init script, don't leave behind
+      userdel mysql || true
     fi
-    rm -rf /run/mysqld # this directory is created by the init script, don't leave behind
-    userdel mysql || true
   fi
 
 fi
diff --git a/debian/mariadb-server.preinst b/debian/mariadb-server.preinst
index 74503f227ffa2..216b98095449a 100644
--- a/debian/mariadb-server.preinst
+++ b/debian/mariadb-server.preinst
@@ -26,7 +26,8 @@ fi
 ${DEBIAN_SCRIPT_TRACE:+ echo "#42#DEBUG# RUNNING $0 $*" 1>&2 }
 
 export PATH=$PATH:/sbin:/usr/sbin:/bin:/usr/bin
-mariadb_datadir=/var/lib/mysql
+mariadb_datadir=/var/lib/mariadb
+legacy_mariadb_datadir=/var/lib/mysql
 mariadb_upgradedir=/var/lib/mysql-upgrade
 
 MARIADBD_USERS="root"
@@ -67,46 +68,53 @@ stop_server() {
   fi
 }
 
-################################ main() ##########################
-
-# @TODO: Rewrite this to use the new upstream /var/lib/mysql_upgrade_info file
-# instead of the legacy /var/lib/debian-XX.X.flag file
-this_version=__MARIADB_MAJOR_VER__
-max_upgradeable_version=5.7
+# Check if the version file mariadb_upgrade_info or mysql_upgrade_info is
+# included with the provided data directory. If it is a MariaDB version, then
+# return the major version number only (XX.XX). Return empty if this directory
+# does not belong to MariaDB.
+get_mariadb_upgrade_info_major_version() {
+  datadir="$1"
 
-# Check if a flag file is found that indicates a previous MariaDB or MySQL
-# version was installed. If multiple flags are found, check which one was
-# the biggest version number.
-for flag in "$mariadb_datadir"/debian-*.flag
-do
-
-  # The for loop leaves $flag as the query string if there are no results,
-  # so the check below is needed to stop further processing when there are
-  # no real results.
-  if [ "$flag" = "$mariadb_datadir/debian-*.flag" ]
+  # Check both mariadb_upgrade_info (higher priority) and mysql_upgrade_info.
+  if [ -f "$datadir/mysql_upgrade_info" ]
   then
-    break
+    read -r full_version < "$datadir/mysql_upgrade_info"
   fi
 
-  # The whole flag_version thing should be rewritten, so ignore minor Shellcheck
-  # nag for now
-  # shellcheck disable=SC2001
-  flag_version=$(echo "$flag" | sed 's/.*debian-\([0-9\.]\+\).flag/\1/')
-
-  # Initialize value if empty
-  if [ -z "$found_version" ]
+  if [ -f "$datadir/mariadb_upgrade_info" ]
   then
-    found_version=$flag_version
+    read -r full_version < "$datadir/mariadb_upgrade_info"
   fi
 
-  # Update value if now bigger then before
-  if dpkg --compare-versions "$flag_version" '>>' "$found_version"
+  # If version is not empty and contains 'MariaDB', get the version number.
+  if [ -n "$full_version" ] && echo "$full_version" | grep -q "MariaDB"
   then
-    found_version=$flag_version
+    # The major version number should the first two components of the version
+    # string (e.g. 11.8 from 11.8.6).
+    echo "$full_version" | awk -F'.' '{print $1"."$2}'
   fi
+}
 
-done
+################################ main() ##########################
+
+this_version=__MARIADB_MAJOR_VER__
+max_upgradeable_version=5.7
 
+# Check for previous mariadb version in the new datadir.
+found_version=$(get_mariadb_upgrade_info_major_version "$mariadb_datadir")
+
+# If nothing was found in the new datadir, check the legacy datadir to see if
+# it has a MariaDB instance.
+if [ -z "$found_version" ] && [ -d "$legacy_mariadb_datadir" ]
+then
+  found_version=$(get_mariadb_upgrade_info_major_version "$legacy_mariadb_datadir")
+
+  # If a mariadb version was found in the legacy datadir, continue using it.
+  if [ -n "$found_version" ]
+  then
+    mariadb_datadir="$legacy_mariadb_datadir"
+  fi
+fi
 
 # If an upgrade is detected, proceed with it automatically without
 # requiring any user interaction.
@@ -117,16 +125,6 @@ done
 # than $max_upgradeable_version.
 if [ -n "$found_version" ]
 then
-
-  # MySQL 8.0 in Ubuntu has a bug in packaging and the file is name wrongly
-  # 'debian-5.7.flag', so in case '5.7' was encountered an extra check needs to
-  # be done to see is there is a file called undo_001, which is a sign of 8.0.
-  if [ "$found_version" == "5.7" ] && [ -f "$mariadb_datadir/undo_001" ]
-  then
-    # Seems to be a 8.0, flag has wrongly 5.7 (know bug)
-    found_version=8.0
-  fi
-
   echo "$mariadb_datadir: found previous version $found_version"
 
   if dpkg --compare-versions "$found_version" '>>' "$this_version"
@@ -142,19 +140,6 @@ then
 
 fi
 
-# If there is no debian-*.flag, and no version was detected, but a file that
-# indicated MySQL 8.0 is found (undo_001 is created by default in MySQL 8.0+
-# installs), then that file is enough of additional indication to trigger the
-# move of the data directory.
-if [ -z "$found_version" ] &&
-   [ -z "$(find $mariadb_datadir/debian-*.flag 2> /dev/null)" ] &&
-   [ -f "$mariadb_datadir/undo_001" ]
-then
-  echo "$mariadb_datadir: no server version flag found, assuming MySQL 8.0 data encountered"
-  downgrade_detected=true
-  found_version="previous" # Just use dummy name as we don't know real version
-fi
-
 # Don't abort dpkg if downgrade is detected (as was done previously).
 # Instead simply move the old datadir and create a new for this_version.
 if [ -n "$downgrade_detected" ]
diff --git a/debian/rules b/debian/rules
index bc0ea43a5a6e2..553db2167158d 100644
--- a/debian/rules
+++ b/debian/rules
@@ -79,8 +79,6 @@ endif
 	# As packages does not have major version any more in package name there is no
 	# way as it not set by dpkg to use this on postinst script. Use sed to
 	# determine major version instead.
-	# @TODO: Rewrite this to use the new upstream /var/lib/mysql_upgrade_info file
-	# instead of the legacy /var/lib/debian-XX.X.flag file
 	sed -i 's/__MARIADB_MAJOR_VER__/$(DEB_VERSION_MAJOR)/g' debian/mariadb-server.post* debian/mariadb-server.preinst
 
 	# Don't build ColumnStore as part of the native build as it does not meet the
diff --git a/debian/salsa-ci.yml b/debian/salsa-ci.yml
index ba0355f84e2f6..ba1fc96326d38 100644
--- a/debian/salsa-ci.yml
+++ b/debian/salsa-ci.yml
@@ -200,10 +200,24 @@ blhc:
   - dpkg -l | grep -iE 'maria|mysql|galera'
   # library tests don't have the mariadb client nor server, so don't check them
 
+.test-verify-using-legacy-data-directory: &test-verify-using-legacy-data-directory
+  # Verify that /var/lib/mysql is still in use as the data directory, and /var/lib/mariadb does not exist.
+  - |
+    test -d /var/lib/mysql || { echo "ERROR: Expected legacy data directory /var/lib/mysql does not exist"; exit 1; }
+    test -d /var/lib/mariadb && { echo "ERROR: Legacy install has new data directory /var/lib/mariadb that should not exist"; exit 1; } || true
+    mariadbd --help --verbose 2>/dev/null | grep --only-matching --perl-regex "datadir[ ]+\K(.*)" | grep /var/lib/mysql/ 1>/dev/null || { echo "ERROR: Legacy install is not using /var/lib/mysql as data directory"; exit 1; }
+
+.test-verify-using-new-data-directory: &test-verify-using-new-data-directory
+  # Verify that /var/lib/mariadb is in use as the data directory.
+  - |
+    test -d /var/lib/mariadb || { echo "ERROR: Expected new data directory /var/lib/mariadb does not exist"; exit 1; }
+    mariadbd --help --verbose 2>/dev/null | grep --only-matching --perl-regex "datadir[ ]+\K(.*)" | grep /var/lib/mariadb/ 1>/dev/null || { echo "ERROR: New install is not using /var/lib/mariadb as data directory"; exit 1; }
+
 .test-verify-final: &test-verify-final |
   dpkg -l | grep -e "mariadb-server.*10\.11"
   mkdir -p debug # Ensure dir exists before using it
   find /var/lib/mysql -ls > debug/var-lib-mysql.list || true # Ignore errors about "no such file or directory"
+  find /var/lib/mariadb -ls > debug/var-lib-mariadb.list || true # Ignore errors about "no such file or directory"
   cp -ra /etc/mysql debug/etc-mysql
   mariadb --skip-column-names -e "select @@version, @@version_comment" # Show version
   mariadb --table -e "SHOW DATABASES;" # List databases
@@ -346,6 +360,7 @@ fresh install:
     - *test-prepare-container
     - *test-install-all
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-new-data-directory
     - *test-verify-final
 
 simple upgrade:
@@ -356,6 +371,7 @@ simple upgrade:
     - apt-get install -qq --yes 'default-mysql*' ${BUILT_PACKAGES}
     - *test-full-upgrade
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb and Bookworm upgrade:
@@ -374,6 +390,7 @@ mariadb and Bookworm upgrade:
     - service mariadb restart
     - *test-full-upgrade
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb-10.6 and Bookworm-20230208 upgrade:
@@ -397,6 +414,7 @@ mariadb-10.6 and Bookworm-20230208 upgrade:
     - *test-full-upgrade
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
     - apt-get purge --yes mariadb*10.?
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb-10.6 and Jammy upgrade:
@@ -423,6 +441,7 @@ mariadb-10.6 and Jammy upgrade:
     # Due to usrmerge, full-upgrade from Jammy to Trixie or newer cannot work
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
     - apt-get purge --yes mariadb*10.?
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb-10.5 and Bullseye upgrade:
@@ -445,6 +464,7 @@ mariadb-10.5 and Bullseye upgrade:
     # Due to usrmerge, full-upgrade from Bullseye to Trixie or newer cannot work
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
     - apt-get purge --yes mariadb*10.?
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb-10.3 and Buster upgrade:
@@ -504,6 +524,7 @@ mariadb-10.3 and Focal upgrade:
     # Give the mariadb-upgrade plenty of time to complete, otherwise next commands
     # fail on non-existing mariadb.sys user
     - sleep 15
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 # Similar to the Cacti install test, check that MariaDB consumer Zoph upgrades
@@ -524,6 +545,7 @@ default-mysql-server and Bookworm upgrade:
     - apt-get install -qq --yes default-mysql-server
     - *test-full-upgrade
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 # Similar to the Cacti install test, check that MariaDB consumer Zoph upgrades
@@ -544,6 +566,7 @@ default-mysql-server and Bullseye upgrade:
     - apt-get install -qq --yes default-mysql-server
     # Due to usrmerge, full-upgrade from Bullseye to Trixie or newer cannot work
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 test basic features:
@@ -552,6 +575,7 @@ test basic features:
     - *test-prepare-container
     - *test-install-all
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-new-data-directory
     - *test-verify-final
     - |
       # Print info about server
@@ -730,6 +754,7 @@ mysql-8.0 in Sid upgrade:
     # the service name 'mariadb' instead, and the fallback is always used.
     - sleep 5 # Give the mysql_upgrade a bit of time to complete before querying the server
     - service mysql status || service mariadb status
+    - *test-verify-using-new-data-directory
     - *test-verify-final
 
 # Upgrading from MySQL 8.0 with datadir in place is not possible. Users need to do a data dump.
@@ -759,6 +784,7 @@ mysql-8.0 in Ubuntu 23.10 upgrade:
     - service mariadb status  # There is no init.d/mysql in MariaDB 10.5+
     # Remove everything MySQL except mysql-common which also MariaDB depends on
     - apt-get purge --yes mysql-s* mysql-cl* libmysql*
+    - *test-verify-using-new-data-directory
     - *test-verify-final
 
 # Upgrading from MySQL 8.0 with datadir in place is not possible. Users need to do a data dump.
@@ -789,6 +815,7 @@ mysql-community-cluster-8.0 from MySQL.com with Bookworm upgrade:
     - systemctl status mysql || true
     - mysql -e 'SELECT VERSION()' || true
     - sleep 5 # Give the mysql_upgrade a bit of time to complete before querying the server
+    - *test-verify-using-new-data-directory
     - *test-verify-final
 
 mariadb.org-10.11 upgrade:
@@ -856,6 +883,7 @@ mariadb.org-10.7 upgrade:
     - *test-verify-initial
     - *test-install-all
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 mariadb.org-10.6 upgrade:
@@ -871,6 +899,7 @@ mariadb.org-10.6 upgrade:
     - *test-verify-initial
     - *test-install-all
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 # archive.mariadb.org for Debian Sid latest is 10.5.13
@@ -885,6 +914,7 @@ mariadb.org-10.5 upgrade:
     - *test-verify-initial
     - *test-install-all
     - service mariadb status # There is no init.d/mysql in MariaDB 10.5+
+    - *test-verify-using-legacy-data-directory
     - *test-verify-final
 
 # archive.mariadb.org for Debian Sid latest is 10.4.17
@@ -1013,4 +1043,5 @@ percona-xtradb-5.7 with Bookworm upgrade:
     # Percona package owned /etc/init.d/mysql, so on removal and upgrade to MariaDB old service name can't be referenced anymore
     - service mariadb status
     - sleep 15 # Give the mysql_upgrade a bit of extra time to complete with MySQL 5.7 before querying the server
+    - *test-verify-using-new-data-directory
     - *test-verify-final
diff --git a/debian/tests/smoke b/debian/tests/smoke
index 5c4facbb5018e..f78b3ca7be1e0 100644
--- a/debian/tests/smoke
+++ b/debian/tests/smoke
@@ -95,7 +95,7 @@ if [ "$(dpkg-architecture -qDEB_HOST_ARCH_BITS)" != 32 ] &&
 then
   dpkg-query -W $plugin
 
-  LOG=/var/lib/mysql/#rocksdb/LOG
+  LOG=/var/lib/mariadb/#rocksdb/LOG
   # XXX: The server may only be started during the install of
   #      mariadb-server, which happens before that of the plugin.
   [ -e $LOG ] || mariadb -e "INSTALL PLUGIN RocksDB SONAME 'ha_rocksdb';"