Fatal error: Call to undefined function variable_get() in C:\UwAmp\www\D8\modules\linkchecker\linkchecker.module on line 2478

When I start Drupal 8 using UwAmp on Win 10 I get

Fatal error: Call to undefined function variable_get() in C:\UwAmp\www\D8\modules\linkchecker\linkchecker.module on line 2478
Call Stack
# Time Memory Function Location
1 0.0010 130216 {main}( ) ...\index.php:0
2 0.9744 12256384 Drupal\Core\DrupalKernel->terminate( ) ...\index.php:22
3 0.9744 12256416 Stack\StackedHttpKernel->terminate( ) ...\DrupalKernel.php:606
4 0.9744 12256456 Symfony\Component\HttpKernel\HttpKernel->terminate( ) ...\StackedHttpKernel.php:32
5 0.9748 12262320 Symfony\Component\EventDispatcher\Debug\TraceableEventDispatcher->dispatch( ) ...\HttpKernel.php:79
6 0.9788 12287088 Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch( ) ...\TraceableEventDispatcher.php:132
7 0.9880 12414608 Symfony\Component\EventDispatcher\Debug\WrappedListener->__invoke( ) ...\ContainerAwareEventDispatcher.php:111
8 0.9881 12415184 call_user_func:{C:\UwAmp\www\D8\vendor\symfony\event-dispatcher\Debug\WrappedListener.php:61} ( ) ...\WrappedListener.php:61
9 0.9881 12415288 Drupal\automated_cron\EventSubscriber\AutomatedCron->onTerminate( ) ...\WrappedListener.php:61
10 0.9887 12417960 Drupal\Core\ProxyClass\Cron->run( ) ...\AutomatedCron.php:65
11 0.9908 12449944 Drupal\Core\Cron->run( ) ...\Cron.php:75
12 0.9979 12467576 Drupal\Core\Cron->invokeCronHandlers( ) ...\Cron.php:120
13 1.0736 13471080 Drupal\Core\Extension\ModuleHandler->invoke( ) ...\Cron.php:200
14 1.0736 13471256 call_user_func_array:{C:\UwAmp\www\D8\core\lib\Drupal\Core\Extension\ModuleHandler.php:391} ( ) ...\ModuleHandler.php:391
15 1.0736 13471432 linkchecker_cron( ) ...\ModuleHandler.php:391
16 1.0741 13474016 _linkchecker_cleanup_links( ) ...\linkchecker.module:380
17 1.0741 13474032 linkchecker_scan_node_types( ) ...\linkchecker.module:1803

The home page is never displayed.

If you need additional information please let me know.