Blank site after 1.7 upgrade?

[jtzako]

I just tried the 1.7 RC1 install from a 1.6.5 test site and ran into a problem. My admin section still works but the main site is blank.

I did not get any errors during the upgrade process and the Extension manager install tab said success afterwards.

Anything I can check to see what went wrong (or fix it)?

[dylanjh]

A blank page normally indicates a PHP error has occurred. However most host providers will disable error reporting to the page to help improve security (error messages can often provide information that will aid in malicious attacks)

The way to find out what the error is, is to enable error reporting within Joomla! which you can do in Site->Global Configuration->server->error reporting

Set it to either simple or maximum.

Load you page up again, and see if an error is shown.

If you still get a blank page, then we to get a little more aggressive,
Edit your /index.php (in the root of your Joomla! install)
and add the following somewhere near the top, within the <?php tag

Code:
error_reporting(E_ALL | E_STRICT);
ini_set("display_errors", 1);


The sadly, the above wil not report parse errors. So if you are still getting a blank page, you need to find out if you have access to error_log which many hosts give these days. If you are unsure, ask your hosting provider for access to your apache error_log file.


Alternatively you can edit your /.htaccess file (create it if it doesnt exist)

and enter

Code:
php_value display_errors 1
php_value display_startup_errors 1


Provided your host supports user htaccess files, this will show any error your site is generating.

Once you have your error, you can start to figure out why its happening.

[jtzako]

OK, I turned on error reporting "simple" and got this error:

Fatal error: Cannot instantiate abstract class JDatabaseQuery in /opt/SBCapache/htdocs/mytestsite/Development/plugins/system/jat3/jat3/core/joomla/modulehelper.php on line 292

I have the latest JAT3 plugin installed, maybe it just isnt compatible with 1.7 yet?

[MonkeyT]

Fatal error: Cannot instantiate abstract class JDatabaseQuery ...

I got something similar to this on a component I have recently written. Here's a cause, which may or may not help you: in 1.7, the Joomla library now includes JDatabaseQueryMySQL and JDatabaseQueryMySQLi classes which are built upon a generic JDatabaseQuery abstract definition - instead of 1.6's JDatabaseQuery Class.

My code called for a new JDatabaseQuery by its classname instead of using the JDatabaseMySQLi::getQuery(TRUE) command. "getQuery(TRUE)" has been updated with the new class definitions so no changes were needed for that code. My guess is JAT3 is unaware of this change.