Plugin wont start

for some reason when I activate the plugin it reports an error message-

Warning: file_put_contents(/home/nelmedia/public_html/wp-config.php): Failed to open stream: Success in /home/nelmedia/public_html/wp-content/plugins/wp-debugging/vendor/wp-cli/wp-config-transformer/src/WPConfigTransformer.php on line 349

Caught Exception: \Fragen\WP_Debugging\Settings::add_constants() – Failed to update the config file.

Any idea?