server-info

No indication of reason of problem. The "Server Info" menu item simply fails to appear on some sites.

Plugin asks to share data upon activation and requires to fill in a form before deactivating. Doesn't even show that much helpful data.

nice after a migration, to know on which server we are

This plugin says that it "... will show you useful information about the hosting server you are using..." including Server OS. It does report SOME useful information about the server OS, but a key aspect NOT included is what OS distribution it is running (e.g. Debian, Ubuntu, Fedora, etc.) When I uninstalled it, it prompted with a question as to why I was uninstalling (I think this is also a good idea, BTW). I provided comments and links to potential locations the author might look to use that will help determine what the distribution is.

This is exactly what I needed. Unfortunately, it didn't work -- or rather, it crashed with two notices: Undefined index 'SERVER_ADDR' and undefined index 'SERVER_ADMIN' and one fatal error "Call to undefined function mysqli_connect()". In all fairness, I'm using version 4.9.4 of Wordpress and the documentation shows that the Server Info plugin hasn't been tested with it. But I didn't expect a fatal error crash. This Wordpress site is on a 3rd party shared hosting platform running IIS. I have a plugin that I am developing that works flawlessly on my other Wordpress sites but fails on this one. I suspect an out-of-date component -- either PHP or MySQL or something unexpected. I was hopeful that the Server Info plugin would help me track down the culprit.

Was I running PHP 5.6 og 7.1 on this website? How much memory is available. MariaDB or MySQL? When troubleshooting you always need this kind of info, and Server Info shows that. No bells and whistles, simple and clean.