“Deprecated function: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in dashboards_preprocess_html() (line 188 of modules/contrib/dashboards/dashboards.module).
The issue appear in the maintenance mode
dashboards_preprocess_html(Array, 'html', Array)
call_user_func_array('dashboards_preprocess_html', Array) (Line: 261)
Drupal\Core\Theme\ThemeManager->render('html', Array) (Line: 480)
Drupal\Core\Render\Renderer->doRender(Array, 1) (Line: 240)
Drupal\Core\Render\Renderer->render(Array, 1) (Line: 153)
Drupal\Core\Render\Renderer->Drupal\Core\Render\{closure}() (Line: 627)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 152)
Drupal\Core\Render\Renderer->renderRoot(Array) (Line: 66)
Drupal\Core\Render\BareHtmlPageRenderer->renderBarePage(Array, Object, 'maintenance_page', Array) (Line: 76)
Drupal\Core\ProxyClass\Render\BareHtmlPageRenderer->renderBarePage(Array, Object, 'maintenance_page') (Line: 164)
Drupal\Core\EventSubscriber\MaintenanceModeSubscriber->onMaintenanceModeRequest(Object, 'site.maintenance_mode_request', Object)
call_user_func(Array, Object, 'site.maintenance_mode_request', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'site.maintenance_mode_request') (Line: 123)
Drupal\Core\EventSubscriber\MaintenanceModeSubscriber->onKernelRequestMaintenance(Object, 'kernel.exception', Object)
call_user_func(Array, Object, 'kernel.exception', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.exception') (Line: 239)
Symfony\Component\HttpKernel\HttpKernel->handleThrowable(Object, Object, 1) (Line: 91)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 191)
Drupal\page_cache\StackMiddleware\PageCache->fetch(Object, 1, 1) (Line: 128)
Drupal\page_cache\StackMiddleware\PageCache->lookup(Object, 1, 1) (Line: 82)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 53)
Asm89\Stack\Cors->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)