diff --git a/Containers/nextcloud/start.sh b/Containers/nextcloud/start.sh
index 10ac59c4..9c0fe07a 100644
--- a/Containers/nextcloud/start.sh
+++ b/Containers/nextcloud/start.sh
@@ -6,6 +6,16 @@ while ! nc -z "$POSTGRES_HOST" 5432; do
     sleep 5
 done
 
+# Use the correct Postgres username
+POSTGRES_USER="oc_$POSTGRES_USER"
+export POSTGRES_USER
+
+# Fix false database connection on old instances
+if [ -f "/var/www/html/config/config.php" ] && sleep 2 && psql -d "postgresql://$POSTGRES_USER:$POSTGRES_PASSWORD@$POSTGRES_HOST:5432/$POSTGRES_DB" -c "select now()"; then
+    sed -i "s|'dbuser'.*=>.*$|'dbuser' => '$POSTGRES_USER',|" /var/www/html/config/config.php
+    sed -i "s|'dbpassword'.*=>.*$|'dbpassword' => '$POSTGRES_PASSWORD',|" /var/www/html/config/config.php
+fi
+
 # Run original entrypoint
 if ! bash /entrypoint.sh; then
     exit 1
diff --git a/Containers/postgresql/Dockerfile b/Containers/postgresql/Dockerfile
index cc97ddaa..3a560c90 100644
--- a/Containers/postgresql/Dockerfile
+++ b/Containers/postgresql/Dockerfile
@@ -17,7 +17,9 @@ RUN set -ex; \
     chown -R postgres:postgres "$PGDATA"
 
 COPY start.sh /usr/bin/
-RUN chmod +x /usr/bin/start.sh
+COPY init-user-db.sh /docker-entrypoint-initdb.d/
+RUN chmod +x /usr/bin/start.sh; \
+    chmod +xr /docker-entrypoint-initdb.d/init-user-db.sh
 
 RUN mkdir /mnt/data; \
     chown postgres:postgres /mnt/data;
diff --git a/Containers/postgresql/init-user-db.sh b/Containers/postgresql/init-user-db.sh
new file mode 100644
index 00000000..b3c8f47f
--- /dev/null
+++ b/Containers/postgresql/init-user-db.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+set -ex
+
+psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-EOSQL
+	CREATE USER "oc_$POSTGRES_USER" WITH PASSWORD "$POSTGRES_PASSWORD";
+	GRANT ALL PRIVILEGES ON DATABASE "$POSTGRES_DB" TO "oc_$POSTGRES_USER";
+EOSQL
+
+set +ex
diff --git a/Containers/postgresql/start.sh b/Containers/postgresql/start.sh
index aad235f5..e4ac9827 100644
--- a/Containers/postgresql/start.sh
+++ b/Containers/postgresql/start.sh
@@ -18,11 +18,13 @@ if ! [ -w "$DUMP_DIR" ]; then
     exit 1
 fi
 
-# # Delete the datadir once (needed for the migration from debian to alpine)
-# if ! [ -f "$DUMP_DIR/initial-cleanup-done" ]; then
-#     rm -rf "${DATADIR:?}/"*
-#     touch "$DUMP_DIR/initial-cleanup-done"
-# fi
+# Delete the datadir once (needed for setting the correct credentials on old instances once)
+if ! [ -f "$DUMP_DIR/export.failed" ] && ! [ -f "$DUMP_DIR/initial-cleanup-done" ]; then
+    set -ex
+    rm -rf "${DATADIR:?}/"*
+    touch "$DUMP_DIR/initial-cleanup-done"
+    set +ex
+fi
 
 # Test if some things match
 # shellcheck disable=SC2235