We also experienced the same issues and contacted Azure Support via Twitter. They suggested to create a forum thread - https://social.msdn.microsoft.com/Forums/en-US/6b185de7-dcdd-4046-bec1-e617da7b5d21/azure-web-app-could-not-find-existent-path-or-file?forum=windowsazurewebsitespreview I think, that if you have not contacted Azure support still - you can subscribe to this forum thread. I will update it as soon as some more data will came in

As requested via Twitter - here is stacktrace:

[DirectoryNotFoundException: Could not find a part of the path 'D:\home\site\wwwroot\App_Plugins\AngularGoogleMaps'.]
   Umbraco.Core.Cache.HttpRuntimeCacheProvider.GetCacheItem(String cacheKey, Func`1 getCacheItem, Nullable`1 timeout, Boolean isSliding, CacheItemPriority priority, CacheItemRemovedCallback removedCallback, CacheDependency dependency) +1056
   Umbraco.Core.Cache.HttpRuntimeCacheProvider.GetCacheItem(String cacheKey, Func`1 getCacheItem, Nullable`1 timeout, Boolean isSliding, CacheItemPriority priority, CacheItemRemovedCallback removedCallback, String[] dependentFiles) +155
   Umbraco.Core.Cache.DeepCloneRuntimeCacheProvider.GetCacheItem(String cacheKey, Func`1 getCacheItem, Nullable`1 timeout, Boolean isSliding, CacheItemPriority priority, CacheItemRemovedCallback removedCallback, String[] dependentFiles) +182
   Umbraco.Core.Manifest.ManifestBuilder.get_PropertyEditors() +356
   Umbraco.Core.PropertyEditors.<>c__DisplayClass8.<.ctor>b__6() +32
   System.Lazy`1.CreateValue() +244
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +31
   System.Lazy`1.get_Value() +14069853
   Umbraco.Core.PropertyEditors.PropertyEditorResolver.GetByAlias(String alias) +74
   Umbraco.Core.PropertyEditors.ValueConverters.JsonValueConverter.IsConverter(PublishedPropertyType propertyType) +40
   System.Linq.WhereEnumerableIterator`1.MoveNext() +176
   System.Linq.Buffer`1..ctor(IEnumerable`1 source) +153
   System.Linq.Enumerable.ToArray(IEnumerable`1 source) +106
   Umbraco.Core.Models.PublishedContent.PublishedPropertyType.InitializeConverters() +238
   Umbraco.Core.Models.PublishedContent.PublishedContentType.<.ctor>b__0(PropertyType x) +45
   System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +223
   System.Linq.Buffer`1..ctor(IEnumerable`1 source) +153
   System.Linq.Enumerable.ToArray(IEnumerable`1 source) +106
   Umbraco.Core.Models.PublishedContent.PublishedContentType..ctor(IContentTypeComposition contentType) +290
   Umbraco.Core.Models.PublishedContent.PublishedContentType.CreatePublishedContentType(PublishedItemType itemType, String alias) +321
   Umbraco.Core.Cache.<>c__DisplayClass9`1.<GetCacheItem>b__8() +15
   System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +84
   Umbraco.Core.Cache.CacheProviderExtensions.GetCacheItem(ICacheProvider provider, String cacheKey, Func`1 getCacheItem) +169
   Umbraco.Core.Models.PublishedContent.PublishedContentType.Get(PublishedItemType itemType, String alias) +354
   Umbraco.Web.PublishedCache.XmlPublishedCache.XmlPublishedContent.Initialize() +2566
   Umbraco.Web.PublishedCache.XmlPublishedCache.XmlPublishedContent..ctor(XmlNode xmlNode, Boolean isPreviewing) +155
   Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.ConvertToDocument(XmlNode xmlNode, Boolean isPreviewing) +50
   Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.DetermineIdByRoute(UmbracoContext umbracoContext, Boolean preview, String route, Boolean hideTopLevelNode) +280
   Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedContentCache.GetByRoute(UmbracoContext umbracoContext, Boolean preview, String route, Nullable`1 hideTopLevelNode) +257
   Umbraco.Web.Routing.ContentFinderByNiceUrl.FindContent(PublishedContentRequest docreq, String route) +261
   Umbraco.Web.Routing.ContentFinderByNiceUrl.TryFindContent(PublishedContentRequest docRequest) +244
   System.Linq.Enumerable.Any(IEnumerable`1 source, Func`2 predicate) +179
   Umbraco.Web.Routing.PublishedContentRequestEngine.FindPublishedContent() +542
   Umbraco.Web.Routing.PublishedContentRequestEngine.FindPublishedContentAndTemplate() +299
   Umbraco.Web.Routing.PublishedContentRequestEngine.PrepareRequest() +124
   Umbraco.Web.UmbracoModule.ProcessRequest(HttpContextBase httpContext) +452
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +142
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) 

I noticed this yesterday too. It knocked my site down for hours and now I can't load any forms in the CMS.

Unable to load form: Could not find a part of the path 'D:\home\site\wwwroot\App_Plugins\UmbracoForms\Data\workflows'.

The folder does exist and so does the json.

I'm looking into this now, it seems clear that an update on Azure caused this to start failing. I'm trying to find the root cause of the failure so we can report back to Microsoft.

Support suggested me to set application settings:

Key: WEBSITE_DYNAMIC_CACHE (all capitals)

Value: 0

After that - I stopped and started web app, waited a little bit and content pops up to me.

I can report we have experienced this too - Azure support also recommended to add that app key which resolved the issue. It is occurring on the new Azure App Service version 58.1.8598.31. Last thing we heard from support was:

At this point we have very limited info on this but we’re investigating and we will let you know as soon as we something to report. For now, we know that this feature conflicts with using Local Cache – are you using this feature by any chance?

Yep - I believe that is correct Seb - if you let me know how I can confirm I will do so.

I can also check it, Sebastiaan, to confirm. But I was not able to locate any version strings for web app version itself

For me, one of the apps with kudu build version 58.50923.2428.0 was not failing and exposes WEBSITE_DYNAMIC_CACHE equal to 0

It says 58.1.8598.22

Cool. Setting "WEBSITE DYNAMIC CACHE" works.

is working on a reply...