Hi Ismail

I've got the same error today and I also running Umbraco ( but 7.15.2) on Azure with a load balancing scenario. One master site (backoffice included) and then Frontend sites (ReadOnly - backoffice not included).

Did you find out something more about this or do you know what causing this error?

My error occurred after deploy on the front end site.

After I've got this error I wanted to restart the front end site. So I downloaded the web.config added a single space and uploaded it back, but I've got the same error after restart.

So I logged in to the backoffice (master site) and run the "Republish entire site". The front end site went back to normal again, but I still don't know what was the probem?

Here is what I find in my log:

 2020-04-17 13:57:29,701 [P4420/D14/T85] ERROR Umbraco.Core.Sync.DatabaseServerMessenger - DISTRIBUTED CACHE IS NOT UPDATED. Failed to execute instructions (id: 3118, instruction count: 1). Instruction is being skipped/ignored
System.ArgumentNullException: Value cannot be null.
Parameter name: contentType
   at Umbraco.Core.Mandate.That[TException](Boolean condition, Func`1 defer)
   at Umbraco.Core.Mandate.ParameterNotNull[T](T value, String paramName)
   at Umbraco.Core.Models.ContentBase..ctor(String name, Int32 parentId, IContentTypeComposition contentType, PropertyCollection properties)
   at Umbraco.Core.Persistence.Factories.ContentFactory.BuildEntity(DocumentDto dto, IContentType contentType, DocumentPublishedReadOnlyDto publishedDto)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.CreateContentFromDto(DocumentDto dto, Sql docSql)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.GetByVersion(Guid versionId)
   at Umbraco.Core.Services.ContentService.GetByVersion(Guid versionId)
   at umbraco.cms.businesslogic.web.Document.setupNode()
   at umbraco.cms.businesslogic.CMSNode..ctor(Int32 Id)
   at umbraco.content.UpdateDocumentCache(Int32 pageId)
   at Umbraco.Web.Cache.PageCacheRefresher.Refresh(Int32 id)
   at Umbraco.Core.Sync.DatabaseServerMessenger.RefreshByIds(Guid uniqueIdentifier, String jsonIds)
   at Umbraco.Core.Sync.DatabaseServerMessenger.NotifyRefreshers(IEnumerable`1 instructions, HashSet`1 processed)
   at Umbraco.Core.Sync.DatabaseServerMessenger.ProcessDatabaseInstructions(IReadOnlyCollection`1 instructionBatch, CacheInstructionDto dto, HashSet`1 processed, Int32& lastId)
 2020-04-17 14:02:55,753 [P4420/D14/T30] ERROR Umbraco.Core.Sync.DatabaseServerMessenger - DISTRIBUTED CACHE IS NOT UPDATED. Failed to execute instructions (id: 3124, instruction count: 2). Instruction is being skipped/ignored
System.ArgumentNullException: Value cannot be null.
Parameter name: contentType
   at Umbraco.Core.Mandate.That[TException](Boolean condition, Func`1 defer)
   at Umbraco.Core.Mandate.ParameterNotNull[T](T value, String paramName)
   at Umbraco.Core.Models.ContentBase..ctor(String name, Int32 parentId, IContentTypeComposition contentType, PropertyCollection properties)
   at Umbraco.Core.Persistence.Factories.ContentFactory.BuildEntity(DocumentDto dto, IContentType contentType, DocumentPublishedReadOnlyDto publishedDto)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.CreateContentFromDto(DocumentDto dto, Sql docSql)
   at Umbraco.Core.Persistence.Repositories.ContentRepository.PerformGet(Int32 id)
   at Umbraco.Core.Cache.DefaultRepositoryCachePolicy`2.Get(TId id, Func`2 performGet, Func`2 performGetAll)
   at Umbraco.Core.Persistence.Repositories.RepositoryBase`2.Get(TId id)
   at Umbraco.Core.Services.ContentService.GetById(Int32 id)
   at umbraco.content.UpdateSortOrder(Int32 contentId)
   at Umbraco.Web.Cache.UnpublishedPageCacheRefresher.Refresh(Int32 id)
   at Umbraco.Core.Sync.DatabaseServerMessenger.RefreshByIds(Guid uniqueIdentifier, String jsonIds)
   at Umbraco.Core.Sync.DatabaseServerMessenger.NotifyRefreshers(IEnumerable`1 instructions, HashSet`1 processed)
   at Umbraco.Core.Sync.DatabaseServerMessenger.ProcessDatabaseInstructions(IReadOnlyCollection`1 instructionBatch, CacheInstructionDto dto, HashSet`1 processed, Int32& lastId)

Best regards Roland

I've seen this one a LOT. That was on 7.6 though and it was supposed to be fixed in 7.8, so if you read the release notes there you should find it.

The gist was that publishing between load balanced nodes had failed because the JSON of the update was too big. It would get stuck trying the failed update every two minutes with this message. The workaround was to find the lastsyncedid file (under App_Data/Temp somewhere IIRC) and delete it, then restart the site.

Thank you Rick!

I will look into the release notes for 7.8 and check the Temp folder next time :)

Best regards Roland

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