diff --git a/CHANGELOG.md b/CHANGELOG.md
index e626cc3..3d0d32e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- [#53] Fix race condition between startup script and post upgrade script
 
 ## [v14.17-2] - 2025-04-24
 
diff --git a/batsTests/post-upgrade.bats b/batsTests/post-upgrade.bats
new file mode 100755
index 0000000..43f7415
--- /dev/null
+++ b/batsTests/post-upgrade.bats
@@ -0,0 +1,290 @@
+#! /bin/bash
+# Bind an unbound BATS variables that fail all tests when combined with 'set -o nounset'
+export BATS_TEST_START_TIME="0"
+export BATSLIB_FILE_PATH_REM=""
+export BATSLIB_FILE_PATH_ADD=""
+
+load '/workspace/target/bats_libs/bats-support/load.bash'
+load '/workspace/target/bats_libs/bats-assert/load.bash'
+load '/workspace/target/bats_libs/bats-mock/load.bash'
+load '/workspace/target/bats_libs/bats-file/load.bash'
+
+setup() {
+  doguctl="$(mock_create)"
+  export doguctl
+  export PATH="${BATS_TMPDIR}:${PATH}"
+  mkdir ${BATS_TMPDIR}/postgresql_bats
+  export PGDATA="${BATS_TMPDIR}/postgresql_bats"
+
+  ln -s "${doguctl}" "${BATS_TMPDIR}/doguctl"
+}
+
+teardown() {
+  /bin/rm "${BATS_TMPDIR}/doguctl"
+  /bin/rm -r "${BATS_TMPDIR}/postgresql_bats"
+}
+
+@test "versionXLessOrEqualThanY() should return true for versions less than or equal to another" {
+  source /workspace/resources/post-upgrade.sh
+
+  run versionXLessOrEqualThanY "1.0.0-1" "1.0.0-1"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "1.0.0-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "1.1.0-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "1.0.2-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "1.0.0-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.1.0-1" "1.1.0-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.2-1" "1.0.2-2"
+  assert_success
+  run versionXLessOrEqualThanY "1.2.3-4" "1.2.3-4"
+  assert_success
+  run versionXLessOrEqualThanY "1.2.3-4" "1.2.3-5"
+  assert_success
+
+  run versionXLessOrEqualThanY "1.0.0-1" "2.0.0-1"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "2.1.0-1"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "2.0.1-1"
+  assert_success
+  run versionXLessOrEqualThanY "1.0.0-1" "2.1.1-1"
+  assert_success
+  run versionXLessOrEqualThanY "5.1.3-1" "5.1.3-1"
+  assert_success
+}
+
+@test "versionXLessOrEqualThanY() should return false for versions greater than another" {
+  source /workspace/resources/post-upgrade.sh
+
+  run versionXLessOrEqualThanY "0.0.0-10" "0.0.0-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-1" "0.0.0-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-1" "0.0.9-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-1" "0.9.9-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-0" "0.9.9-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.1.0-1" "0.0.0-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-1" "0.0.9-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-1" "0.9.9-9"
+  assert_failure
+  run versionXLessOrEqualThanY "1.0.0-0" "0.9.9-9"
+  assert_failure
+
+  run versionXLessOrEqualThanY "1.2.3-4" "0.1.2-3"
+  assert_failure
+  run versionXLessOrEqualThanY "1.2.3-5" "0.1.2-3"
+  assert_failure
+
+  run versionXLessOrEqualThanY "2.0.0-1" "1.0.0-1"
+  assert_failure
+  run versionXLessOrEqualThanY "2.1.0-1" "1.0.0-1"
+  assert_failure
+  run versionXLessOrEqualThanY "2.0.1-1" "1.0.0-1"
+  assert_failure
+  run versionXLessOrEqualThanY "2.1.1-1" "1.0.0-1"
+  assert_failure
+}
+
+@test "runPostUpgrade should exit early if no version change" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+
+  mock_set_output "${doguctl}" "true" 1
+  mock_set_status "${doguctl}" 0 2
+  run runPostUpgrade "1.0.0-1" "1.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "2"
+  assert_line "startPostgresql is mocked"
+  assert_line "FROM and TO versions are the same; Exiting..."
+}
+
+@test "runPostUpgrade should also restrict stat visibility if no version change" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+  restrictStatVisibility() {
+    echo "restrictStatVisibility is mocked"
+  }
+
+  mock_set_output "${doguctl}" "false" 1
+  mock_set_status "${doguctl}" 0 2
+  run runPostUpgrade "1.0.0-1" "1.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "2"
+  assert_line "startPostgresql is mocked"
+  assert_line "Postgresql stats might be visible outside of their intended scope. Restricting stat visibility..."
+  assert_line "restrictStatVisibility is mocked"
+  assert_line "FROM and TO versions are the same; Exiting..."
+}
+
+@test "runPostUpgrade should reindexAllDatabases on version upgrade" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+  reindexAllDatabases() {
+    echo "reindexAllDatabases is mocked"
+  }
+  versionXLessOrEqualThanY() {
+    echo "versionXLessOrEqualThanY is mocked"
+    return 0
+  }
+  killPostgresql() {
+    echo "killPostgresql is mocked"
+  }
+
+  mock_set_output "${doguctl}" "true" 1
+  mock_set_output "${doguctl}" "true" 2
+  mock_set_status "${doguctl}" 0 3
+  run runPostUpgrade "1.0.0-1" "2.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "3"
+  assert_line "startPostgresql is mocked"
+  assert_line "Postgresql version changed. Reindexing all databases..."
+  assert_line "reindexAllDatabases is mocked"
+  assert_line "versionXLessOrEqualThanY is mocked"
+  assert_line "killPostgresql is mocked"
+}
+
+@test "runPostUpgrade should restrict stats visibility if not already restricted" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+  restrictStatVisibility() {
+    echo "restrictStatVisibility is mocked"
+  }
+  reindexAllDatabases() {
+    echo "reindexAllDatabases is mocked"
+  }
+  versionXLessOrEqualThanY() {
+    echo "versionXLessOrEqualThanY is mocked"
+    return 0
+  }
+  killPostgresql() {
+    echo "killPostgresql is mocked"
+  }
+
+  # stats not yet restricted
+  mock_set_output "${doguctl}" "false" 1
+  mock_set_output "${doguctl}" "true" 2
+  mock_set_status "${doguctl}" 0 3
+  run runPostUpgrade "1.0.0-1" "2.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "3"
+  assert_line "startPostgresql is mocked"
+  assert_line "Postgresql stats might be visible outside of their intended scope. Restricting stat visibility..."
+  assert_line "restrictStatVisibility is mocked"
+  assert_line "reindexAllDatabases is mocked"
+  assert_line "versionXLessOrEqualThanY is mocked"
+  assert_line "killPostgresql is mocked"
+}
+
+@test "runPostUpgrade should restore db dump if dump file exists" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  prepareForBackup() {
+    echo "prepareForBackup is mocked"
+    isBackupAvailable=true
+  }
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+  restoreBackup() {
+    echo "restoreBackup is mocked"
+  }
+  reindexAllDatabases() {
+    echo "reindexAllDatabases is mocked"
+  }
+  versionXLessOrEqualThanY() {
+    echo "versionXLessOrEqualThanY is mocked"
+    return 0
+  }
+  killPostgresql() {
+    echo "killPostgresql is mocked"
+  }
+
+  tmpfile="${PGDATA}/postgresqlFullBackup.dump"
+  touch "$tmpfile"  # Create the file
+
+
+  # stats not yet restricted
+  mock_set_output "${doguctl}" "true" 1
+  mock_set_output "${doguctl}" "true" 2
+  mock_set_status "${doguctl}" 0 3
+  run runPostUpgrade "1.0.0-1" "2.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "3"
+  assert_line "prepareForBackup is mocked"
+  assert_line "startPostgresql is mocked"
+  assert_line "restoreBackup is mocked"
+  assert_line "reindexAllDatabases is mocked"
+  assert_line "versionXLessOrEqualThanY is mocked"
+  assert_line "killPostgresql is mocked"
+
+  # Cleanup: Remove the file
+  rm "$tmpfile"
+}
+
+@test "runPostUpgrade should migrateConstraintsOnPartitionedTables if not yet migrated" {
+  source /workspace/resources/post-upgrade.sh
+
+  # Mock the functions
+  startPostgresql() {
+    echo "startPostgresql is mocked"
+  }
+  reindexAllDatabases() {
+    echo "reindexAllDatabases is mocked"
+  }
+  versionXLessOrEqualThanY() {
+    echo "versionXLessOrEqualThanY is mocked"
+    return 0
+  }
+  migrateConstraintsOnPartitionedTables() {
+    echo "migrateConstraintsOnPartitionedTables is mocked"
+  }
+  killPostgresql() {
+    echo "killPostgresql is mocked"
+  }
+
+  mock_set_output "${doguctl}" "true" 1
+  mock_set_output "${doguctl}" "false" 2
+  mock_set_status "${doguctl}" 0 3
+  run runPostUpgrade "1.0.0-1" "2.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${doguctl}")" "3"
+  assert_line "startPostgresql is mocked"
+  assert_line "Postgresql version changed. Reindexing all databases..."
+  assert_line "reindexAllDatabases is mocked"
+  assert_line "versionXLessOrEqualThanY is mocked"
+  assert_line "migrateConstraintsOnPartitionedTables is mocked"
+  assert_line "killPostgresql is mocked"
+}
diff --git a/batsTests/pre-upgrade.bats b/batsTests/pre-upgrade.bats
new file mode 100755
index 0000000..3261a60
--- /dev/null
+++ b/batsTests/pre-upgrade.bats
@@ -0,0 +1,64 @@
+#! /bin/bash
+# Bind an unbound BATS variables that fail all tests when combined with 'set -o nounset'
+export BATS_TEST_START_TIME="0"
+export BATSLIB_FILE_PATH_REM=""
+export BATSLIB_FILE_PATH_ADD=""
+
+load '/workspace/target/bats_libs/bats-support/load.bash'
+load '/workspace/target/bats_libs/bats-assert/load.bash'
+load '/workspace/target/bats_libs/bats-mock/load.bash'
+load '/workspace/target/bats_libs/bats-file/load.bash'
+
+setup() {
+  pg_dumpall="$(mock_create)"
+  doguctl="$(mock_create)"
+  export pg_dumpall
+  export doguctl
+  export PATH="${BATS_TMPDIR}:${PATH}"
+  export PGDATA="/var/lib/postgresql"
+  ln -s "${pg_dumpall}" "${BATS_TMPDIR}/pg_dumpall"
+  ln -s "${doguctl}" "${BATS_TMPDIR}/doguctl"
+}
+
+teardown() {
+  rm "${BATS_TMPDIR}/pg_dumpall"
+  rm "${BATS_TMPDIR}/doguctl"
+}
+
+@test "runPreUpgrade should do nothing on equal versions" {
+  source /workspace/resources/pre-upgrade.sh
+
+  run runPreUpgrade "1.0.0-1" "1.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${pg_dumpall}")" "0"
+  assert_equal "$(mock_get_call_num "${doguctl}")" "0"
+  assert_line 'FROM and TO versions are the same; Exiting...'
+}
+
+@test "runPreUpgrade should just set local_state on minor upgrade" {
+  source /workspace/resources/pre-upgrade.sh
+  mock_set_status "${doguctl}" 0
+
+  run runPreUpgrade "1.0.0-1" "1.1.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${pg_dumpall}")" "0"
+  assert_equal "$(mock_get_call_num "${doguctl}")" "1"
+  assert_line 'Set registry flag so startup script waits for post-upgrade to finish...'
+}
+
+@test "runPreUpgrade should set local_state and save dump on major upgrade" {
+  source /workspace/resources/pre-upgrade.sh
+  mock_set_status "${doguctl}" 0
+  mock_set_status "${pg_dumpall}" 0
+
+  run runPreUpgrade "1.0.0-1" "2.0.0-1"
+
+  assert_success
+  assert_equal "$(mock_get_call_num "${pg_dumpall}")" "1"
+  assert_equal "$(mock_get_call_num "${doguctl}")" "1"
+  assert_line "Dumping database to /var/lib/postgresql/postgresqlFullBackup.dump..."
+  assert_line "Finished dumping database"
+  assert_line 'Set registry flag so startup script waits for post-upgrade to finish...'
+}
diff --git a/resources/post-upgrade.sh b/resources/post-upgrade.sh
index cee6695..84402e4 100755
--- a/resources/post-upgrade.sh
+++ b/resources/post-upgrade.sh
@@ -3,8 +3,71 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
-FROM_VERSION="${1}"
-TO_VERSION="${2}"
+# shellcheck disable=SC1091
+source "$(dirname "${BASH_SOURCE[0]}")/util.sh"
+
+function prepareForBackup() {
+    isBackupAvailable=true
+    # Moving backup and emptying PGDATA directory
+    mv "${PGDATA}"/postgresqlFullBackup.dump /tmp/postgresqlFullBackup.dump
+
+    # New PostgreSQL version requires completely empty folder
+    rm -rf "${PGDATA:?}"/.??*
+    rm -rf "${PGDATA:?}"/*
+
+    initializePostgreSQL
+}
+
+function startPostgresql() {
+    echo "start postgresql"
+    gosu postgres postgres &
+    PID=$!
+
+    while ! pg_isready >/dev/null; do
+      # Postgres is not ready yet to accept connections
+      sleep 0.1
+    done
+}
+
+function restoreBackup() {
+    echo "Restoring database dump..."
+    psql -U postgres -f /tmp/postgresqlFullBackup.dump postgres
+    rm /tmp/postgresqlFullBackup.dump
+    echo "Restoring database dump...complete!"
+}
+
+# see https://www.postgresql.org/docs/14/release-14-12.html#:~:text=Restrict%20visibility%20of,WITH%20ALLOW_CONNECTIONS%20false%3B for more information
+function restrictStatVisibility() {
+    if [ ! -f /usr/share/postgresql/fix-CVE-2024-4317.sql ]; then
+        return 0
+    fi
+
+    while ! pg_isready >/dev/null; do
+        # Postgres is not ready yet to accept connections
+        sleep 0.1
+    done
+    # temporarily accept connections on template0
+    psql -U postgres -c "ALTER DATABASE template0 WITH ALLOW_CONNECTIONS true;"
+
+    # get all tables
+    psql -U postgres -c "SELECT d.datname as \"Name\" FROM pg_catalog.pg_database d;" -X > databases
+    # there are four lines of sql result information (two at the start, two at the end)
+    for i in $(seq 3 $(($(wc -l < databases) - 2 ))); do
+        DATABASE_NAME=$(sed "${i}!d" databases | xargs)
+        psql -U postgres -d "${DATABASE_NAME}" -c "\i /usr/share/postgresql/fix-CVE-2024-4317.sql"
+    done
+    # disable connections on template0
+    psql -U postgres -c "ALTER DATABASE template0 WITH ALLOW_CONNECTIONS false;"
+    doguctl config restricted_stat_visibility true
+}
+
+function reindexAllDatabases() {
+    while ! pg_isready >/dev/null; do
+        # Postgres is not ready yet to accept connections
+        sleep 0.1
+    done
+    reindexdb -U postgres --verbose --all
+}
 
 # versionXLessOrEqualThanY returns true if X is less than or equal to Y; otherwise false
 function versionXLessOrEqualThanY() {
@@ -114,58 +177,63 @@ function migrateConstraintsOnPartitionedTables() {
     doguctl config migrated_database_constraints true
 }
 
-# see https://www.postgresql.org/docs/14/release-14-12.html#:~:text=Restrict%20visibility%20of,WITH%20ALLOW_CONNECTIONS%20false%3B for more information
-function restrictStatVisibility() {
-    if [ ! -f /usr/share/postgresql/fix-CVE-2024-4317.sql ]; then
-        return 0
-    fi
+function killPostgresql() {
+    # Kill postgres
+    pkill -P ${PID}
+    kill ${PID}
 
-    while ! pg_isready >/dev/null; do
-        # Postgres is not ready yet to accept connections
-        sleep 0.1
+    while pgrep -x postgres >/dev/null; do
+      # Postgres is still running
+      sleep 0.1
     done
-    # temporarily accept connections on template0
-    psql -U postgres -c "ALTER DATABASE template0 WITH ALLOW_CONNECTIONS true;"
+    echo "postgresql successfully killed (this is expected during post upgrade)"
+}
 
-    # get all tables
-    psql -U postgres -c "SELECT d.datname as \"Name\" FROM pg_catalog.pg_database d;" -X > databases
-    # there are four lines of sql result information (two at the start, two at the end)
-    for i in $(seq 3 $(($(wc -l < databases) - 2 ))); do
-        DATABASE_NAME=$(sed "${i}!d" databases | xargs)
-        psql -U postgres -d "${DATABASE_NAME}" -c "\i /usr/share/postgresql/fix-CVE-2024-4317.sql"
-    done
+function runPostUpgrade() {
+    FROM_VERSION="${1}"
+    TO_VERSION="${2}"
 
-    # disable connections on template0
-    psql -U postgres -c "ALTER DATABASE template0 WITH ALLOW_CONNECTIONS false;"
+    isBackupAvailable=false
+    if [ -e "${PGDATA}"/postgresqlFullBackup.dump ]; then
+        prepareForBackup
+    fi
 
-    doguctl config restricted_stat_visibility true
-}
+    startPostgresql
 
-function reindexAllDatabases() {
-    while ! pg_isready >/dev/null; do
-        # Postgres is not ready yet to accept connections
-        sleep 0.1
-    done
-    reindexdb -U postgres --verbose --all
-}
+    if [ "${isBackupAvailable}" = "true" ]; then
+        restoreBackup
+    fi
 
-if [[ $(doguctl config --default "false" restricted_stat_visibility) != "true" ]] ; then
-    # Postgres 14.12 (Dogu Version 14.15-2) fixed an issue with the visibility of hidden statistics
-    # since this fix comes after the version was released, always execute it if it was not executed before
-    echo "Postgresql stats might be visible outside of their intended scope. Restricting stat visibility..."
-    restrictStatVisibility
-fi
+    if [[ $(doguctl config --default "false" restricted_stat_visibility) != "true" ]] ; then
+        # Postgres 14.12 (Dogu Version 14.15-2) fixed an issue with the visibility of hidden statistics
+        # since this fix comes after the version was released, always execute it if it was not executed before
+        echo "Postgresql stats might be visible outside of their intended scope. Restricting stat visibility..."
+        restrictStatVisibility
+    fi
+    if [ "${FROM_VERSION}" = "${TO_VERSION}" ]; then
+        echo "FROM and TO versions are the same; Exiting..."
+        doguctl config --rm "local_state"
+        exit 0
+    else
+        echo "Postgresql version changed. Reindexing all databases..."
+        reindexAllDatabases
+    fi
 
-if [ "${FROM_VERSION}" = "${TO_VERSION}" ]; then
-    echo "FROM and TO versions are the same; Exiting..."
-    exit 0
-else
-    echo "Postgresql version changed. Reindexing all databases..."
-    reindexAllDatabases
-fi
+    if versionXLessOrEqualThanY "0.14.15-1" "0.${TO_VERSION}" && [[ $(doguctl config --default "false" migrated_database_constraints) != "true" ]] ; then
+        # Postgres 14.14 (Dogu Version 14.15.x) fixed an issue with constraints on partitioned tables
+        # If any partitioned tables have constraints on them, this migration removes and readds them
+        migrateConstraintsOnPartitionedTables
+    fi
+
+    killPostgresql
+
+    echo "Removing local_state registry flag so startup script can start afterwards..."
+    doguctl config --rm "local_state"
+
+    echo "Postgresql post-upgrade done"
+}
 
-if versionXLessOrEqualThanY "0.14.15-1" "0.${TO_VERSION}" && [[ $(doguctl config --default "false" migrated_database_constraints) != "true" ]] ; then
-    # Postgres 14.14 (Dogu Version 14.15.x) fixed an issue with constraints on partitioned tables
-    # If any partitioned tables have constraints on them, this migration removes and readds them
-    migrateConstraintsOnPartitionedTables
+# make the script only run when executed, not when sourced from bats tests
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    runPostUpgrade "$@"
 fi
diff --git a/resources/pre-upgrade.sh b/resources/pre-upgrade.sh
index caffd44..3dadfe3 100755
--- a/resources/pre-upgrade.sh
+++ b/resources/pre-upgrade.sh
@@ -3,14 +3,29 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
-FROM_VERSION="${1}"
-TO_VERSION="${2}"
-FROM_MAJOR_VERSION=$(echo "${FROM_VERSION}" | cut -d '.' -f1)
-TO_MAJOR_VERSION=$(echo "${TO_VERSION}" | cut -d '.' -f1)
+function runPreUpgrade() {
+  FROM_VERSION="${1}"
+  TO_VERSION="${2}"
+  FROM_MAJOR_VERSION=$(echo "${FROM_VERSION}" | cut -d '.' -f1)
+  TO_MAJOR_VERSION=$(echo "${TO_VERSION}" | cut -d '.' -f1)
 
-# dump database if TO_MAJOR_VERSION is higher than FROM_MAJOR_VERSION
-if [[ "${TO_MAJOR_VERSION}" -gt "${FROM_MAJOR_VERSION}" ]]; then
-    echo "Dumping database to ${PGDATA}/postgresqlFullBackup.dump..."
-    pg_dumpall -U postgres -f "${PGDATA}"/postgresqlFullBackup.dump
-    echo "Finished dumping database"
+  # dump database if TO_MAJOR_VERSION is higher than FROM_MAJOR_VERSION
+  if [[ "${TO_MAJOR_VERSION}" -gt "${FROM_MAJOR_VERSION}" ]]; then
+      echo "Dumping database to ${PGDATA}/postgresqlFullBackup.dump..."
+      pg_dumpall -U postgres -f "${PGDATA}"/postgresqlFullBackup.dump
+      echo "Finished dumping database"
+  fi
+
+  if [ "${FROM_VERSION}" = "${TO_VERSION}" ]; then
+    echo "FROM and TO versions are the same; Exiting..."
+    exit 0
+  fi
+
+  echo "Set registry flag so startup script waits for post-upgrade to finish..."
+  doguctl config "local_state" "upgrading"
+}
+
+# make the script only run when executed, not when sourced from bats tests
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+  runPreUpgrade "$@"
 fi
diff --git a/resources/startup.sh b/resources/startup.sh
index ce82657..bdf6526 100755
--- a/resources/startup.sh
+++ b/resources/startup.sh
@@ -3,6 +3,9 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
+# shellcheck disable=SC1091
+source "$(dirname "${BASH_SOURCE[0]}")/util.sh"
+
 function mask2cidr() {
   local storedIFS="${IFS}"
   NBITS=0
@@ -77,32 +80,6 @@ function write_pg_hba_conf() {
   create_hba >"${PGDATA}"/pg_hba.conf
 }
 
-function initializePostgreSQL() {
-  # set stage for health check
-  doguctl state installing
-
-  # install database
-  gosu postgres initdb
-
-  # postgres user
-  POSTGRES_USER="postgres"
-
-  # store the user
-  doguctl config user "${POSTGRES_USER}"
-
-  # create random password
-  POSTGRES_PASSWORD=$(doguctl random)
-
-  # store the password encrypted
-  doguctl config -e password "${POSTGRES_PASSWORD}"
-
-  # open port
-  sed -ri "s/^#(listen_addresses\s*=\s*)\S+/\1'*'/" "$PGDATA"/postgresql.conf
-
-  # set generated password
-  echo "ALTER USER ${POSTGRES_USER} WITH SUPERUSER PASSWORD '${POSTGRES_PASSWORD}';" | gosu 2>/dev/null 1>&2 postgres postgres --single -jE
-}
-
 function waitForPostgreSQLStartup() {
   while ! pg_isready >/dev/null; do
     # Postgres is not ready yet to accept connections
@@ -149,38 +126,17 @@ function runMain() {
   mkdir -p /run/postgresql
   chown postgres:postgres /run/postgresql
 
-  if [ -z "$(ls -A "$PGDATA")" ]; then
-    initializePostgreSQL
-    write_pg_hba_conf
-  elif [ -e "${PGDATA}"/postgresqlFullBackup.dump ]; then
-    # Moving backup and emptying PGDATA directory
-    mv "${PGDATA}"/postgresqlFullBackup.dump /tmp/postgresqlFullBackup.dump
-    # New PostgreSQL version requires completely empty folder
-
-    rm -rf "${PGDATA:?}"/.??*
-    rm -rf "${PGDATA:?}"/*
+  # check whether post-upgrade script is still running
+  while [[ "$(doguctl config "local_state" -d "empty")" == "upgrading" ]]; do
+    echo "Upgrade script is running. Waiting..."
+    sleep 3
+  done
 
+  if [ -z "$(ls -A "$PGDATA")" ]; then
     initializePostgreSQL
-
-    echo "Restoring database dump..."
-    # Start postgres to restore backup
-    gosu postgres postgres &
-    PID=$!
-    waitForPostgreSQLStartup
-    # Restore backup
-    psql -U postgres -f /tmp/postgresqlFullBackup.dump postgres
-    rm /tmp/postgresqlFullBackup.dump
-    # Kill postgres
-    pkill -P ${PID}
-    kill ${PID}
-    waitForPostgreSQLShutdown
-    echo "Database dump successfully restored"
-
-    write_pg_hba_conf
-  else
-    write_pg_hba_conf
   fi
 
+  write_pg_hba_conf
   setDoguLogLevel
 
   # set stage for health check
diff --git a/resources/util.sh b/resources/util.sh
new file mode 100644
index 0000000..10e83c5
--- /dev/null
+++ b/resources/util.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+set -o errexit
+set -o nounset
+set -o pipefail
+
+
+function initializePostgreSQL() {
+  # set stage for health check
+  doguctl state installing
+
+  # install database
+  gosu postgres initdb
+
+  # postgres user
+  POSTGRES_USER="postgres"
+
+  # store the user
+  doguctl config user "${POSTGRES_USER}"
+
+  # create random password
+  POSTGRES_PASSWORD=$(doguctl random)
+
+  # store the password encrypted
+  doguctl config -e password "${POSTGRES_PASSWORD}"
+
+  # open port
+  sed -ri "s/^#(listen_addresses\s*=\s*)\S+/\1'*'/" "$PGDATA"/postgresql.conf
+
+  # set generated password
+  echo "ALTER USER ${POSTGRES_USER} WITH SUPERUSER PASSWORD '${POSTGRES_PASSWORD}';" | gosu 2>/dev/null 1>&2 postgres postgres --single -jE
+}
\ No newline at end of file