Hello,

we are having issue we a website version 7.5.8.

the site goes down very often. We are getting the below errors :

System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found.

at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes) 2019-12-16 09:44:13,261 [P6024/D2/T110] WARN Umbraco.Web.UmbracoModule - Status code is 404 yet TrySkipIisCustomErrors is false - IIS will take over. 2019-12-16 09:44:45,074 [P6024/D2/T104] ERROR Umbraco.Core.Dynamics.DynamicInstanceHelper - An error occurred finding and executing extension method "Isfirst" for type "Umbraco.Web.Models.DynamicPublishedContent". Types searched for extension methods were Umbraco.Web.Models.DynamicPublishedContent. System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found. at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes) 2019-12-16 09:44:45,074 [P6024/D2/T104] ERROR Umbraco.Core.Dynamics.DynamicInstanceHelper - An error occurred finding and executing extension method "Isfirst" for type "Umbraco.Web.Models.DynamicPublishedContent". Types searched for extension methods were Umbraco.Web.Models.DynamicPublishedContent. System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found. at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes) 2019-12-16 09:44:45,074 [P6024/D2/T104] ERROR Umbraco.Core.Dynamics.DynamicInstanceHelper - An error occurred finding and executing extension method "Isfirst" for type "Umbraco.Web.Models.DynamicPublishedContent". Types searched for extension methods were Umbraco.Web.Models.DynamicPublishedContent. System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found. at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes) 2019-12-16 09:44:45,074 [P6024/D2/T104] ERROR Umbraco.Core.Dynamics.DynamicInstanceHelper - An error occurred finding and executing extension method "Isfirst" for type "Umbraco.Web.Models.DynamicPublishedContent". Types searched for extension methods were Umbraco.Web.Models.DynamicPublishedContent. System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found. at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes) 2019-12-16 09:44:45,074 [P6024/D2/T104] ERROR Umbraco.Core.Dynamics.DynamicInstanceHelper - An error occurred finding and executing extension method "Isfirst" for type "Umbraco.Web.Models.DynamicPublishedContent". Types searched for extension methods were Umbraco.Web.Models.DynamicPublishedContent. System.MissingMethodException: Method 'Umbraco.Web.Models.DynamicPublishedContent.Isfirst' not found. at Umbraco.Core.Dynamics.DynamicInstanceHelper.FindAndExecuteExtensionMethod[T](IRuntimeCacheProvider runtimeCache, T thisObject, Object[] args, String name, IEnumerable1 findMethodsOnTypes) at Umbraco.Core.Dynamics.DynamicInstanceHelper.TryInvokeMember[T](IRuntimeCacheProvider runtimeCache, T thisObject, InvokeMemberBinder binder, Object[] args, IEnumerable1 findExtensionMethodsOnTypes)

Can someone please help.

Regards,

Kusum