This is with a fresh install of 10.1.2 on a bare-bones site with only admin_toolbar, views_slideshow and entityqueue installed. Page throws an error upon save of a new views display and log and reports the following message. View is, indeed, saved, however.
I have a bunch of displays I need to create and so far, it's happened every time. I'll report back if not.
Suggestions greatly apreciated...
Symfony\Component\Routing\Exception\RouteNotFoundException: Route "view.slideshow.page_3" does not exist. in Drupal\Core\Routing\RouteProvider->getRouteByName() (line 206 of core/lib/Drupal/Core/Routing/RouteProvider.php).
Drupal\Core\Routing\UrlGenerator->getRoute('view.slideshow.page_3') (Line: 276)
Drupal\Core\Routing\UrlGenerator->generateFromRoute('view.slideshow.page_3', Array, Array, 1) (Line: 108)
Drupal\Core\Render\MetadataBubblingUrlGenerator->generateFromRoute('view.slideshow.page_3', Array, Array, 1) (Line: 765)
Drupal\Core\Url->toString(1) (Line: 183)
Drupal\Core\Utility\LinkGenerator->generate(Object, Object) (Line: 95)
Drupal\Core\Render\Element\Link::preRenderLink(Array)
call_user_func_array(Array, Array) (Line: 111)
Drupal\Core\Render\Renderer->doTrustedCallback(Array, Array, 'Render #pre_render callbacks must be methods of a class that implements \Drupal\Core\Security\TrustedCallbackInterface or be an anonymous function. The callback was %s. See https://www.drupal.org/node/2966725', 'exception', 'Drupal\Core\Render\Element\RenderCallbackInterface') (Line: 788)
Drupal\Core\Render\Renderer->doCallback('#pre_render', Array, Array) (Line: 377)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 238)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 583)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 239)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 128)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 171)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
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: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->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: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
UPDATE: Next one saved without error. Will report back... thanks...