diff -u b/core/modules/dblog/src/Logger/DbLog.php b/core/modules/dblog/src/Logger/DbLog.php
--- b/core/modules/dblog/src/Logger/DbLog.php
+++ b/core/modules/dblog/src/Logger/DbLog.php
@@ -84,12 +84,23 @@
         ->execute();
     }
     catch (\Exception $e) {
+      // When running Drupal on MySQL or Maria DB you can run in several errors
+      // that corrupt the database connection. Some examples for these kind of
+      // errors on the database layer are "1100 - Table 'xyz' was not locked
+      // with LOCK TABLES" and "1153 – Got a packet bigger than
+      // ‘max_allowed_packet’ bytes". If such an error happens, the MySQL server
+      // invalidates the connection and answers all further request through this
+      // connection by "2006 - MySQL server had gone away". In that case the
+      // insert statement above results in a database exception. To ensure that
+      // the causal error is written to the log we try once to open a dedicated
+      // connection and write again.
       if (
+        // Only handle database related exceptions.
         ($e instanceof DatabaseException || $e instanceof \PDOException) &&
+        // Avoid an endless loop of re-write attempts.
         $this->connection->getTarget() != self::DEDICATED_DBLOG_CONNECTION_TARGET
       ) {
-        // Open a dedicated connection for logging to ensure that errors that
-        // messed up the default connection are still logged.
+        // Open a dedicated connection for logging.
         $key = $this->connection->getKey();
         $info = Database::getConnectionInfo($key);
         Database::addConnectionInfo($key, self::DEDICATED_DBLOG_CONNECTION_TARGET, $info['default']);