Blank pages in Moodle after install - failed to install php5-mysql

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Do you happen to have php5-pgsql installed? (apt-cache policy php5-pgsql)

Look like I do have php5-pgsql installed.

apt-cache policy php5-pgsql

php5-pgsql:
  Installed: 5.2.4-2ubuntu5.1
  Candidate: 5.2.4-2ubuntu5.1
  Version table:
 *** 5.2.4-2ubuntu5.1 0
        500 http://gb.archive.ubuntu.com hardy-updates/main Packages
        100 /var/lib/dpkg/status
     5.2.4-2ubuntu5 0
        500 http://gb.archive.ubuntu.com hardy/main Packages

Moodle uses either mysql or pgsql as it database backend. Since you have installed php5-pgsql, it does'nt install php5-mysql as part of its dependency.

Also after the configuration screen where you get to select the database,username,password, etc., you will be warned that the script cannot connect to the server (Failed to connect to database: Can't connect to local MySQL server through socket...)

I did not know that I had php5-pgsql installed.
And it took me two hours to track down the problem.

On Ubuntu, the script asks me to select either
"Postgres" or "Mysql" - I selected Mysql - at that point
the script should check that I have php5-mysql installed.

PLEASE NOTE: The script does not fail to connect with the
database. It successfully creates an empty database
(called moodle in my case). SO I GET NO ERROR MESSAGE
FROM THE INSTALL SCRIPT. (Could it be that the script
does not need php5-mysql ?).

Setting status to confirmed as i am able to replicate it (Test case A). (not sure if test case B produce the same result though. )

Dependency is an either-or type (php5-pgsql | php5-mysql). Therefore when user has either one installed, but has chosen a option that required the other to be needed, the webpage could not load. There was no warning from the postinst script as it uses perl (DBI) to connect to the database.

Test case:
(A) mysql
0) Ensure mysql is installed and running and php5-mysql is not installed
1) sudo apt-get install moodle
2) Select mysql and enter database details

(B) pgsql
0) Ensure pgsql is installed and running and php5-pgsql is not installed
1) sudo apt-get install moodle
2) Select mysql and enter database details

Actual result
The postinst script created a table in the database (correct behaviour).
However when going to the moodle webpage (http://localhost/moodle/admin), php error occurs. The error is caused by missing php5-mysql.

Expected result.
The postinst script created a table in the database
Moodle webpage works.

Rui got it right. The problem is that we need to fix the dependencies as he describes. You can install moodle without php5-mysql installed, so you get a blank screen when you go to moodle. A Normal Person (our audience) has no idea what the problem is. I went to install phpmyadmin to investigate the problem and when I did I noticed that php5-mysql got installed and lo! the problem was resolved.

This is a quick fix with no side-effects that I can imagine. It'd be nice to get this in before 8.10 gets released.

This is still a bug in 8.10. I 'tested' it today :-(

This appears to me to not necessarily be a straightforward fix necessarily. My reading of this is that if you have php5-mysql or php5-pgsql already installed but then choose the other one in the moodle install configuration you end up with problems.

I don't think there is any dependence issue really here from how I read this, but rather an issue with the debconf questions asked during install.

The only thing I can think of to get around that would be to check what database the user has installed and only ask them to choose if they have both installed, otherwise we just go with the one they have installed. Does that make sense?

What makes this issue even more complicated to handle transparently is the fact that the Dependencies (php5-pgsql | php5-mysql) and (postgresql-client | mysql-client) as well as the Recommends (postgresql | mysql-server) seems to be handled/picked separately. That is, you can have both mysql-server and mysql-client installed and apt will satisfy its dependencies by choosing to install php5-pgsql.

On another note. A quick, and incomplete, solution which might at least help somewhat could be to simply switch the order of the postgres- and mysql-dependencies, putting mysql first. I could be wrong, but I'm guessing that people without any special preferences usually takes the mysql track.

I'm not sure what we're going to be able to do with this but I think we know what the problem is, marking as Triaged.

This bug was fixed in the package moodle - 1.9.4.dfsg-0ubuntu1

---------------
moodle (1.9.4.dfsg-0ubuntu1) jaunty; urgency=low

  * Merge with Debian git (Closes LP: #322961, #239481, #334611):
    - use Ubuntu's smarty lib directory for linking
    - use internal yui library
    - add update-notifier support back in

  [Matt Oquist]
    * renamed prerm script
    * significantly rewrote postinst and other maintainer scripts to improve
      user experience and package maintainability
      (Closes LP: #225662, #325450, #327843, #303078, #234609)

moodle (1.9.4.dfsg-1) UNRELEASED; urgency=low

  * New Upstream Version (closes: #475535, #514284, #515823)
    (added notes/ and tag/ to debian/install)
  * Merge with Ubuntu:
    - drop use of wwwconfig (closes: #389502, #302205)
    - debian/postinst: ucf fixes (fixes a hang)

  * Remove preinst (no more direct upgrades from sarge)
  * Remove PHP4 support from the Apache config file we provide
  * Drop support for apache 1.x and remove from debconf
  * Add swedish debconf translation (closes: #511202)

  * Bump debhelper compatibility to 7
  * Add lintian overrides for known customised libraries
  * Add new license files to delete (lintian warning)
  * Compress the deb with bzip2
  * Add a watch file
  * Update copyright file

  Dependencies:
  * Depend on libjs-yui instead of yui (renamed after lenny)
  * Add dependency on unzip
  * Recommend php5-xmlrpc and aspell
  * Suggest clamav
  * Demoted mimetex to recommended

  Generated config:
  * Turn 'dbpersist' on by default in the generated config.php
  * Include whitespace warning at the end of generated config.php
  * Set the path to du, unzip and zip

moodle (1.8.2.dfsg-4) unstable; urgency=high

  * Improve the fix for log URL filtering as suggested by Steffen Joeris
    (MSA-09-0007 / CVE-2009-0500)
  * Backport upstream fix for calendar export leakage
    (MSA-09-0006 / CVE-2009-0501)

moodle (1.8.2.dfsg-3) unstable; urgency=high

  * Delete unused (but vulnerable) Spellchecker plugin to htmlarea
    (MSA-09-0005, CVE-2008-5153)
  * Hide images of deleted users (MSA-09-0001)
  * Fix user pix disclosure (MSA-09-0002)
  * Fix XSS vulnerabilities in HTML blocks (MSA-09-0004)
  * Fix XSS vulnerabilities in logs (MSA-09-0007)
  * Fix CSRF vulnerability in forum code (MSA-09-0008)

moodle (1.8.2.dfsg-2) unstable; urgency=high

  [ Dan Poltawski ]
  * Patch SQL injection bug in hotpot module (MSA-08-0010)
  * Fix XSS bug in logged urls (MDL-11414)
  * Fix XSS bug in install script (MSA-08-0004)
  * Fix insufficient access control in Login as feature (MSA-08-0003)
  * Profiles of deleted users were accessible allowing for spam (MSA-08-0015)
  * Deficincy in text cleaning functions allowed for XSS (MSA-08-0021)
  * Fix CSRF in messaging settings (MSA-08-0023)
  * Fix anonymous group creation and html injection (MDL-11759)
  * Fix SQL injection bug in mnet (MDL-9288)
  * Fix SQL injection bug in restore (MDL-11857)
  * Insufficient cleaning of essay questions (MDL-12079)
  * Fix insufficient cleaning of PARAM_HOST (MDL-12793)
  * Fix XSS bug in logged urls (MDL-11414)
  * Fix uncleaned params in wiki (MDL-14806)

  [ Francois Marier ]
  * Update ht...