Internal Error 500 with link from FP to CP

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at root@localhost to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

Hello…

Shows this when, from frontend of WP website, admin logged in, i click on the function the recall the DB of admin CP.
If i manually add ‘index.php’ After It works properly. But it s not now It Is supposed to do.
Any suggestion? Thanks

FULL CONVERSATION https://wordpress.org/support/topic/internal-error-500-with-link-from-fp-to-cp/#post-17471142

Ok, I tryed deactivating the theme, and putting twenty-twenty four standard WP theme, and trying to click the button, and still the error was appearing. 

I reactivated my theme.

Then I started trying to deactivating plugin and see which one could be the problem

I managed to guess the plugin which was defecting at first try.

As soon I deactivated the “WP Travel Engine – Elementor widgets”, and went back on the main page, tried to click the link and everything worked fine.

I activated back again, and doesn’t work anymore the link.

This means that the plugin doesn’t make things works properly.

Attached a screenshot though of the 2 plugin that I use, the second one is the engine that develop the function I need, the first one is the integration with element that shows the module / widget on the website to have the function of the second plugin available to be used from users.

How to fix this? Because if I deactivate the plugin I can’t show on the website the widget and everything become pretty useless.

Thank you