Internal server error following login

[jsharris]

When logging in to Nagios XI, using either an AD account or nagiosadmin, in IE the result is HTTP 500 Internal Server Error (when friendly error messages are turned on and a blank page when not) while in Firefox the result is a blank page. Alerts appear to still get generated but we cannot monitor anything. No system changes have been made since we upgraded a few weeks ago.

Have not yet found anything in any searches to determine the cause. Has anyone else come across this problem or have any suggestions for a fix?

[hsmith]

I have a few questions:

What version of XI? Are you using SSL? Are you having this issue with any other browsers? If you open up the console/firebug with F12, do you see anything telling when you try to load the page?

[jsharris]

Not sure as to what version we are currently running (nothing on the about page) as we just, minutes ago, upgraded to whatever the latest stable version is in an attempt to resolve. Not using SSL. Having trouble with IE 11, Firefox, Chrome; no other browsers installed. Tried emulating IE 10 with the same result.

F12 (network tab) only indicates an attempted HTTP POST with the result being 500 Internal Server Error.

[hsmith]

I don't think the upgrade should have touched the firewall, but maybe it did. Can you post the output of a service iptables status command?

[jsharris]

Here is the output:

Table: filter
Chain INPUT (policy ACCEPT)
num target prot opt source destination
1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED, ESTABLISHED
2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0
3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
5 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:80
6 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:443
7 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW udp dpt:162
8 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:5667
9 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with ic mp-host-prohibited

Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with ic mp-host-prohibited

Chain OUTPUT (policy ACCEPT)
num target prot opt source destination

[rkennedy]

Can you navigate to the XI web interface and then post the output of the following 4 commands?

tail -n50 /var/log/httpd/error_log
tail -n50 /var/log/httpd/ssl_error_log
tail -n50 /var/log/httpd/access_log
tail -n50 /var/log/httpd/ssl_access_log

[jsharris]

What is the path for the web interface?

[tmcdonald]

It should be whatever you have been using to log in already, usually something like http://192.168.1.100/nagiosxi

[jsharris]

Gotcha; thought you meant a file location for the UI files.

That known, however, we still have the problem of how do I run that command if I am unable to log in to Nagios? We enter our credentials and get either a blank page or Internal Server Error. I can grab the files you want the data from directly but I cannot perform any actions through the GUI at this time.

[tmcdonald]

The commands we are asking you to run should be run from the command line, not the web interface. Attempt a web interface login, then run the commands from the CLI and show their output.