Halt on Login - Return blank page

Halt on Login - Return blank page

by A. H. -
Number of replies: 16

I can't log in - I just stay stuck on the login screen

The most common cause for this is that your own computer (not your Moodle server) has a firewall that is stripping referrer information from the browser. Here are some instructions for fixing Norton firewall products.

The server admin can also fix this for everyone by changing the secureforms variable to 'No' in the security section of Administration >> Configuration >> Variables.

Another possible cause of this problem is that sessions are not configured properly on the server. You can test this by calling the script http://yourserver/moodle/lib/session-test.php.

*****************************************************************************

However, our production server has been running for quite sometime and this problem started existing couple of days ago! All the time we had the "secureforms" set to YES.

We have the application on 1 server and DB on another server. Both servers are 2x3.2GHZ Xeon, 4GB RAM, Server2003,IIS 6,mysql 4.1.7,PHP 5.1.2.


What do you think is happening to the servers? Why are we being stuck every now and then on the login page?



Thank you for your help,

amer


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In reply to A. H.

Re: Halt on Login - Return blank page

by A. H. -
Continuing...

The same problem existed when we once added 5000 students to a group on AD (we're using LDAP for Auth/Enrol). It was a course in which we wanted to enroll 5000 students, so we created the group on AD in the student OU. Moodle then started halting on login page every now and then. But now, we dont have any group having 5000 users.

Another question here arises, why the step above didnt work?
What is the limit for number of members (students) in a group (course)?
What will happen when we have 1000 groups (courses) with 50 students each?

This is a very serious problem we're currently facing. We never ever felt that theres a limitation on WebCT sad.

amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by Ken Wilson -
Amer

This may be helpful owing to the number of users you have...

1. AD has limits on the maximum number of concurrent queries and rows returned. You have to use NTDSUTIL.EXE to amend these. See this Microsoft document (http://support.microsoft.com/default.aspx?scid=kb;en-us;315071&sd=tech).

2. Also, Iñaki is (reportedly!) working on a fix for the 1000 limit on the number of objects returned in a query. See Dan Stowell's post in this thread (http://moodle.org/mod/forum/discuss.php?d=50124).

As a note, we have about about 1400 students in separate OUs in AD (on 2 DCs) and we have no problems.

Ken
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In reply to A. H.

Re: Halt on Login - Return blank page

by Iñaki Arenaza -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers
If the problems started a couple of days ago, then see what has changed at that time. If something is working and suddlenly stops, most probably it's due to some changes to the program, the servers, the environment, etc.

Saludos. Iñaki.
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In reply to Iñaki Arenaza

Re: Halt on Login - Return blank page

by A. H. -
Dear Moodlers,
I need to know what should i suspect. The MySQL database or network? The servers are connected via a switch. The switch ports are managed by another departmment. My question is, how can i know if this problem is due to db or network?After that i can start solving the problem. Are there any applications that help me diagnose?

Thnx for the help in advance
amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by A. H. -
Dear All,
I dont know why I am not getting any help on this topic but my director can no more tolerate this and is thinking of renewing WebCT license. I am enjoying administering Moodle mainly because it is open source, but i get so stressed when I find no hints on what to do! The problem is that the above problem is occuring on our Production server and we already started giving workshops on how to use moodle and how to shift from WebCT...

amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by Iñaki Arenaza -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers
Nothing personal. It's just that your setup is unknown for me (I don't use IIS and I don't know how to monitor or troubleshot it). I'm sorry you are having those problems but as I already said, if it's been working so far and it started showing the problema a few days ago, then something has changed in your setup (and someone has to know what and why).

If that's nos the case (very unlikely) then the other way to diagnose this is to debug the login code and see where it's getting stuck.

I'm afraid this is the only help I can provide...

Saludos. Iñaki.
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In reply to A. H.

Re: Halt on Login - Return blank page

by Ken Wilson -

Amer

Iñaki suggestion seems to make sense. Something must have been changed in AD. Have your network users notice any degredation in login times?

If you're sure that nothing has been changed, search the User Authentication section of the forums, especially this thread http://moodle.org/mod/forum/discuss.php?d=37749. It could simply be a PHP or MySQL timeout issue or a negotiation problem on the switch.

In situations like this, it is best to start from the basics: hardware first (network leads, switch, network cards, etc), then the software.

Let us know how you get on!

Ken

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In reply to Ken Wilson

Re: Halt on Login - Return blank page

by A. H. -
Hi,
whats wierd is that sometimes it lets me log in and sometimes it halts. The problem is that the Domain Controller belongs to another department. However, I contacted the other dpt. and they said when am sure that the problem is not from my side, I contact them again so that they check from their side. So, how should i be sure that the problem is not from code or the database which is on another server?

Am trying now and i appreciate if any one has any new hints. The only difference or changes that are happening are that I groups on LDAP are increasing everyday and more and more students are being enrolled.
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In reply to A. H.

Re: Halt on Login - Return blank page

by Viorel Tabara -
Hello Amer,

I would definitely look at Inaki's suggestion to add some debugging options to the login code, so you'll know where it gets stuck. That's the beauty of open source...

Also, if you suspect network issues, run Ethereal and look at the results - the 'netstat' command comes in handy here, too.

The community can provide better sugestions if you provide as much information as you can about your setup, logs, etc.

Hope that helps,
Viorel
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In reply to Viorel Tabara

Re: Halt on Login - Return blank page

by A. H. -
Thank you all for your support. I will try to give as much details as possible about my settings.

Basics: The details are written above in a previous post.
Test Env.: There is a testserver which has the SAME exact instance as the one existing on the production server.All code modified is found in these 2 instances. The code is first tested on testserver and then replicated to production server. Thus, currently, both servers are running the same code.So there is no problem in the code because it is working great on the test server.

On testserver, the application and database are on 1 machine whereas on the production server, there is 1 server that has the application and 1 server for db.

On testserver there is only around 10 users whereas on production server there is now around 1400 user.

On production server, at these time, there is only me logging in. So there is no network traffic.

I doubted in MySQL and network. These are the only differences between these 2 setups.

P.S.: Both servers are connected to the same LDAP server and are on the same subnet.

amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by Iñaki Arenaza -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers
When you say you get stuck in the login screen, do you get an error? if so, what error?

If you don't get an error, does the page time-out? Does it seem to load for ever?

Does it return you to the login page without any error at all?

Saludos. Iñaki.
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In reply to Iñaki Arenaza

Re: Halt on Login - Return blank page

by A. H. -
No error. you wait for like a minute and then get a blank page saying in the status bar: Done.
If you refresh, it takes you back to the login page.

amer
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In reply to Iñaki Arenaza

Re: Halt on Login - Return blank page

by A. H. -
Moreover, a problem exists when I am trying to change from LDAP authentication to Manual accounts only. When you click on save changes, the page goes on and on and am not able to change the option.

amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by Viorel Tabara -
There are several things you can do in order to troubleshoot your problem - if modifying the code in order to add more debugging information is not suitable, this is what I would do:

1.when it halts run the http://yourserver/moodle/lib/session-test.php - on my servers the 1st run returns "No session found - starting a session now. Reload this page" and after reload "Session found - welcome back! Sessions are working correctly. Reload this page".

2.build a new DB server so I can have the same configuration as in the production environment.

3.look in the event logs.

4.enable performance monitoring and get data from cpu, memory, disk activity and network traffic.

5.debug the http requests (wget and curl in linux - there should be something similar for windows - look in the microsoft newgroups - usually I follow MVPs geeks advices) ; other tools exists on microsoft's scripting website.

6.run sysinternals files and registry monitoring tools on the application server or anywhere you would ask yourself "what the heck is goig on here?".

7.enable debugging on the database server and look at the sql statements.

8.use tcpdump for network traffic analysis.

This is what I would start with - once you get into it, more ideas will come and that's how you learn. Windows sometimes needs to be hacked in order to get more information, so once you isolate the problem focus on getting your hands on tools that will allow you to understand what's going on behind the scenes.

Good luck,
Viorel
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In reply to Viorel Tabara

Re: Halt on Login - Return blank page

by A. H. -
Dear  Viorel,
Thank you alot of the steps. I will follow and check for results.

But as an update:
I removed 1.5.3 and deployed 1.5.4 and the problem stil existed.
I recently discovered using TCPview, that once one logs in, it opens around 10 tcp sessions, but they then close after a minute. But the thing is that why does it open this much? But in moodledata/sessions, only 1 session opens.

Will update you.

amer
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In reply to A. H.

Re: Halt on Login - Return blank page

by Iñaki Arenaza -
Picture of Core developers Picture of Documentation writers Picture of Particularly helpful Moodlers Picture of Peer reviewers Picture of Plugin developers
Maybe the browser is opening several connections to the web server in order to fetch objects (images, css, js files, etc.) in parallel.

Saludos. Iñaki.
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