Piwigo will show errors right at the top of the page, or in your browser console.

Server logs: Ask your hoster or check your server software documentation.

I would suggest following the advice erAck gave you when you asked the question a month and a half ago.
[Forum, topic 29105] Edit user freeze

Also, keep your related questions together in one topic, instead of starting a new one each time. Then people trying to help you don't need to go searching around. Thanks.