Hi! I have been using K2 (Version 2.10.3) on an old Joomla 3.9.24. I have recently upgraded the server (Microsoft-IIS/8.5) to PHP 7.4.7 and MySQL 8.0.23.

Although Joomla works ok, it seems that I can't post new K2 items since (MySQL "syntax error 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')}' at line 1").

My question is, is there any workaround, or should I downgrade MySQL?

Thanks in advance

Thanks for your answer. I have already changed the authentication plugin as per the guide you have provided, or else Joomla 3 wouldn't start.

Joomla works fine, only new items in K2 are not saved. It most probably has to do with a query not compatible with MySQL 8?

Thanks again.

Here is the example of the debug log (with setting "Log almost everything" set to on) when trying to save a new K2 item:

#Date: 2021-02-09 16:06:34 UTC
#Software: Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

#Fields: datetime priority clientip category message
2021-02-09T16:06:34+00:00 ERROR **.**.**.** database-error Database query failed (error # 1064): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')}' at line 1
2021-02-09T16:06:34+00:00 CRITICAL **.**.**.** error Uncaught \Throwable of type JDatabaseExceptionExecuting thrown. Stack trace: #0 C:\[undisclosed-path]\libraries\joomla\database\database.php(33): JDatabaseDriverMysqli->execute()
#1 C:\[undisclosed-path]\administrator\components\com_k2\models\item.php(664): JDatabase->query()
#2 C:\[undisclosed-path]\administrator\components\com_k2\controllers\item.php(27): K2ModelItem->save()
#3 C:\[undisclosed-path]\libraries\src\MVC\Controller\BaseController.php(710): K2ControllerItem->save()
#4 C:\[undisclosed-path]\administrator\components\com_k2\k2.php(147): Joomla\CMS\MVC\Controller\BaseController->execute()
#5 C:\[undisclosed-path]\libraries\src\Component\ComponentHelper.php(402): require_once('C:\\inetpub\\Priv...')
#6 C:\[undisclosed-path]\libraries\src\Component\ComponentHelper.php(377): Joomla\CMS\Component\ComponentHelper::executeComponent()
#7 C:\[undisclosed-path]\libraries\src\Application\AdministratorApplication.php(101): Joomla\CMS\Component\ComponentHelper::renderComponent()
#8 C:\[undisclosed-path]\libraries\src\Application\AdministratorApplication.php(159): Joomla\CMS\Application\AdministratorApplication->dispatch()
#9 C:\[undisclosed-path]\libraries\src\Application\CMSApplication.php(196): Joomla\CMS\Application\AdministratorApplication->doExecute()
#10 C:\[undisclosed-path]\administrator\index.php(51): Joomla\CMS\Application\CMSApplication->execute()
#11 {main}

Still the same error. Additional (probably similar) problem: Items wont get trashed.

Thanks. Unfortunately, K2 v2.10.4 [Dev Build 20210205] still shows the same error (1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1) when trying to insert any item.

Moreover, there are no errors shown, however, items cannot be trashed or modified.