When you found error regarding 'max_execution_time' exceed, then you can follow steps for resolve this error:
Steps:
You can put the below given code in drupal 8 index.php file.
ini_set('max_execution_time', 120); //for 120 seconds
ini_set('max_execution_time', 0); //for infinite process
OR
You can add below given code in settings.php file. (sites/default/settings.php)
ini_set('max_execution_time', 120); //for 120 seconds
ini_set('max_execution_time', 0); //for infinite process
Both will work for resolve that error.
Note: If have any suggestions or issue regarding 'How to resolve max execution time error in drupal ?' then you can ask by comments.
