diff --git a/lib/dml/pgsql_native_moodle_database.php b/lib/dml/pgsql_native_moodle_database.php
index 98becbc6289..67f213cd5be 100644
--- a/lib/dml/pgsql_native_moodle_database.php
+++ b/lib/dml/pgsql_native_moodle_database.php
@@ -653,7 +653,7 @@ class pgsql_native_moodle_database extends moodle_database {
                 $id = reset($row);
                 if ($blobs) {
                     foreach ($blobs as $blob) {
-                        $row[$blob] = pg_unescape_bytea($row[$blob]);
+                        $row[$blob] = $row[$blob] !== null ? pg_unescape_bytea($row[$blob]) : null;
                     }
                 }
                 if (isset($return[$id])) {
diff --git a/lib/dml/pgsql_native_moodle_recordset.php b/lib/dml/pgsql_native_moodle_recordset.php
index 525a48c916a..41093740e0c 100644
--- a/lib/dml/pgsql_native_moodle_recordset.php
+++ b/lib/dml/pgsql_native_moodle_recordset.php
@@ -62,7 +62,7 @@ class pgsql_native_moodle_recordset extends moodle_recordset {
 
         if ($this->blobs) {
             foreach ($this->blobs as $blob) {
-                $row[$blob] = pg_unescape_bytea($row[$blob]);
+                $row[$blob] = $row[$blob] !== null ? pg_unescape_bytea($row[$blob]) : null;
             }
         }