I'm having an issue upgrading a quickstart package from 3.3.6 to 3.8. I initially tried a direct upgrade through the Joomla update component but this failed with a 500 error. I enabled error reporting and get the following error:
Fatal error: Call to undefined method JApplicationAdministrator::isClient() in /home/mydomain/public_html/plugins/system/stats/stats.php on line 82
I then restored from backup and tried a 3.4 upgrade package and received the same error. I also tried uploading a 3.4, 3.5, 3.6 full package and extracting over the existing site but I still get the same error.
I renamed the stats folder and just got a blank white screen on the admin even though error reporting was enabled. I checked the error log and it reports:
[27-Sep-2017 23:30:00 Europe/London] PHP Fatal error: Call to undefined method JApplicationAdministrator::isClient() in /home/mydomain/public_html/plugins/quickicon/phpversioncheck/phpversioncheck.php on line 204
So i renamed the phpversioncheck folder and could access the admin panel....brilliant, I'm now on J3.4
I next try an update to 3.5. I cannot update through the Ext installation method i.e. Extensions > Extension Manager > Install > Upload Package file ('m not sure what version of Joomla this became obsolete) and when I go to Components > Joomla Update > Options i get:
Fatal error: Call to undefined method JApplicationAdministrator::isClient() in /home/mydomain/public_html/administrator/components/com_fields/models/fields.php on line 230
So..I then just try an update to 3.8 through the update component (what the hell) and get:
Fatal error: Call to undefined method JApplicationAdministrator::isClient() in /home/mydomain/public_html/plugins/system/logout/logout.php on line 48
Following this I start renaming folders as I get the errors such as: stats (again) remember redirect
I'm running out of idea's so If anyone has any idea's it would be most welcome :)
Thank you in advance.