I have a Joomla extension which is built for Joomla 1.5. At the moment I'm upgrading the extension to work with Joomla 3.0
I updated old deprecated php functions in the new version of the extension.
The problem is when I activate the extension on my Joomla 3 site and I try to login into the backend, I get the following error:
Fatal error: Call to a member function get() on null in [my joomla folder]/libraries/vendor/joomla/application/src/AbstractApplication.php on line 126
Does anybody had this error before? If so, how can this be solved?
I've read the documentation of Joomla 1.5 & 3. What I've seen during my research is that this error usually occurs when you try to load a Joomla 1.5 template into a Joomla 3 website. But in this situation it's totally different. The problem resides in the extension. But I can't figure out which function is causing the issue. It could be that the old J 1.5 code is still in the extension, too bad Joomla does not have a way of searching through deprecated Joomla functions.
When I add a debug_backtrace() I get all arrays printed on the screen, but after that I get: Error: Failed to start application: Failed to start the session because headers have already been sent by "[joomla dir]/libraries/vendor/joomla/application/src/AbstractApplication.php" at line 128.
I placed the debug_backtrace() before the return in the get method. (So I don't get to see a complete array list).
The last array I get to see before the error:
 => Array ( [file] => /[joomla dir]/index.php [line] => 46 [function] => getApplication [class] => Joomla\CMS\Factory [type] => :: [args] => Array (  => site ) )