Warning: date() expects parameter 2 to be integer, array given in date_iso8601() (line 343 of /home/qb46532/public_html/d8site/c

I have upgraded my website to Drupal 8 from Drupal 7. Recently after upgrading, I noticed the following. Can someone guide me how to resolve this issue or point me to the right platform where I can post this issue if this is not the right forum for this issue?

Warning: date() expects parameter 2 to be integer, array given in date_iso8601() (line 343 of /home/qb46532/public_html/d8site/core/includes/common.inc) #0 /home/qb46532/public_html/d8site/core/includes/bootstrap.inc(584): _drupal_error_handler_real(2, 'date() expects ...', '/home/qb46532/p...', 343, Array) #1 [internal function]: _drupal_error_handler(2, 'date() expects ...', '/home/qb46532/p...', 343, Array) #2 /home/qb46532/public_html/d8site/core/includes/common.inc(343): date('c', Array) #3 /home/qb46532/public_html/d8site/core/modules/rdf/rdf.module(190): date_iso8601(Array, NULL) #4 /home/qb46532/public_html/d8site/core/modules/rdf/rdf.module(220): rdf_rdfa_attributes(Array, Array) #5 [internal function]: rdf_entity_prepare_view('node', Array, Array, 'full') #6 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Extension/ModuleHandler.php(403): call_user_func_array('rdf_entity_prep...', Array) #7 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(317): DrupalCoreExtensionModuleHandler->invokeAll('entity_prepare_...', Array) #8 /home/qb46532/public_html/d8site/core/modules/node/src/NodeViewBuilder.php(22): DrupalCoreEntityEntityViewBuilder->buildComponents(Array, Array, Array, 'full') #9 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(263): DrupalnodeNodeViewBuilder->buildComponents(Array, Array, Array, 'full') #10 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(220): DrupalCoreEntityEntityViewBuilder->buildMultiple(Array) #11 [internal function]: DrupalCoreEntityEntityViewBuilder->build(Array) #12 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/Renderer.php(378): call_user_func(Array, Array) #13 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/Renderer.php(195): DrupalCoreRenderRenderer->doRender(Array, false) #14 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(226): DrupalCoreRenderRenderer->render(Array, false) #15 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/Renderer.php(582): DrupalCoreRenderMainContentHtmlRenderer->DrupalCoreRenderMainContent{closure}() #16 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(227): DrupalCoreRenderRenderer->executeInRenderContext(Object(DrupalCoreRenderRenderContext), Object(Closure)) #17 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(117): DrupalCoreRenderMainContentHtmlRenderer->prepare(Array, Object(SymfonyComponentHttpFoundationRequest), Object(DrupalCoreRoutingCurrentRouteMatch)) #18 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php(90): DrupalCoreRenderMainContentHtmlRenderer->renderResponse(Array, Object(SymfonyComponentHttpFoundationRequest), Object(DrupalCoreRoutingCurrentRouteMatch)) #19 [internal function]: DrupalCoreEventSubscriberMainContentViewSubscriber->onViewRenderArray(Object(SymfonyComponentHttpKernelEventGetResponseForControllerResultEvent), 'kernel.view', Object(DrupalComponentEventDispatcherContainerAwareEventDispatcher)) #20 /home/qb46532/public_html/d8site/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(111): call_user_func(Array, Object(SymfonyComponentHttpKernelEventGetResponseForControllerResultEvent), 'kernel.view', Object(DrupalComponentEventDispatcherContainerAwareEventDispatcher)) #21 /home/qb46532/public_html/d8site/vendor/symfony/http-kernel/HttpKernel.php(156): DrupalComponentEventDispatcherContainerAwareEventDispatcher->dispatch('kernel.view', Object(SymfonyComponentHttpKernelEventGetResponseForControllerResultEvent)) #22 /home/qb46532/public_html/d8site/vendor/symfony/http-kernel/HttpKernel.php(68): SymfonyComponentHttpKernelHttpKernel->handleRaw(Object(SymfonyComponentHttpFoundationRequest), 1) #23 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/StackMiddleware/Session.php(57): SymfonyComponentHttpKernelHttpKernel->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #24 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): DrupalCoreStackMiddlewareSession->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #25 /home/qb46532/public_html/d8site/core/modules/page_cache/src/StackMiddleware/PageCache.php(99): DrupalCoreStackMiddlewareKernelPreHandle->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #26 /home/qb46532/public_html/d8site/core/modules/page_cache/src/StackMiddleware/PageCache.php(78): Drupalpage_cacheStackMiddlewarePageCache->pass(Object(SymfonyComponentHttpFoundationRequest), 1, true) #27 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupalpage_cacheStackMiddlewarePageCache->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #28 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(52): DrupalCoreStackMiddlewareReverseProxyMiddleware->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #29 /home/qb46532/public_html/d8site/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): DrupalCoreStackMiddlewareNegotiationMiddleware->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #30 /home/qb46532/public_html/d8site/core/lib/Drupal/Core/DrupalKernel.php(665): StackStackedHttpKernel->handle(Object(SymfonyComponentHttpFoundationRequest), 1, true) #31 /home/qb46532/public_html/d8site/index.php(19): DrupalCoreDrupalKernel->handle(Object(SymfonyComponentHttpFoundationRequest)) #32 {main}.
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