Error: Document info is blank. Users getting error trying to open a file.

Hi All. An on-prem customer on 8.5 (using only web) is often getting an error upon opening a document.

When looking in the netserver log, it looks like the file isn't written to the temp-folder. Or at least thats my guess.

NOTE: Its not for every user, and it only happens a couple pr. day, so I guess it can be network-related.

What is next step to test? I do not understand much of the logged details unfortunately.

Level:   Error
At:      07:04:42

Element:
Message: Service call Document.CheckinDocument failed with exception
Document.CheckinDocument
Type:    SuperOffice.Exceptions.SoException
Details:
   at SuperOffice.CRM.Services.Implementation.DocumentAgentLocal.CheckinDocument(Int32 documentId, String[] allowedReturnTypes, String versionDescription, String[] versionExtraFields)
   at SuperOffice.TrayApp.Server.TrayAppServer.<>c__DisplayClass3_0.<CheckinDocument>b__0(CheckinDocumentResponse response)
   at SuperOffice.TrayApp.Server.TrayAppServer.Execute[TRequest,TResponse](TRequest request, OnExecute`2 implementation)

Inner Element:
Message: Document info is blank.
Type:    System.IO.FileNotFoundException
Details:
   at SuperOffice.CRM.Documents.SoArc2CheckoutHelper.GetLockFileName(IDocumentInfo documentInfo)
   at SuperOffice.CRM.Documents.SoArc2CheckoutHelper.GetCheckoutData(IDocumentInfo documentInfo)
   at SuperOffice.CRM.Documents.SoArc2.GetCheckoutState(IDocumentInfo documentInfo)
   at SuperOffice.CRM.Documents.PhysicalDocument.CheckWriteAccess(IDocumentInfo incomingInfo)
   at SuperOffice.CRM.Documents.PhysicalDocument.CheckinDocument(String[] allowedReturnTypes, String versionDescription, String[] versionExtraFields)
   at SuperOffice.CRM.Services.Implementation.BL.DocumentEntityImplementation.CheckinDocument(Int32 documentId, String[] allowedReturnTypes, String versionDescription, String[] versionExtraFields)
   at SuperOffice.CRM.Services.Implementation.DocumentAgentLocal.CheckinDocument(Int32 documentId, String[] allowedReturnTypes, String versionDescription, String[] versionExtraFields)

Environment info:
User:                           gbrsa (872) - Authorized
Role:                           (Employee)User level 1: Superuser: has full access to data, but cannot maintain the system
SingleThreadMode:               False
IsWebToolsContext:              true
IsTrayAppWcfContext:            true
Database type:                  MSSQL - 14
Database:                       \\*removed*\SuperOffice (crm8), Database serial #: 1410014334, Database Expiration Date: 12. februar 2022
DatabaseServer:                 *removed*
DatabaseName:                   *removed*
SerialNumber:                   1410014334
Version:                        SuperOffice NetServer 8.5 Release (Build: Release85_C-2020.01.09-03)
Version.Assembly:               8.5.0.0
Version.File:                   8.5.7313.1732
Version.BuildLabel:             Release85_C-2020.01.09-03
ContextIdentifier:              Default
MachineName:                    *removed*
StackTrace:                        at SuperOffice.Diagnostics.SoLogger.LogError(Exception ex)
   at SuperOffice.TrayApp.Server.TrayAppServer.Execute[TRequest,TResponse](TRequest request, OnExecute`2 implementation)
   at SuperOffice.TrayApp.Server.TrayAppServer.CheckinDocument(CheckinDocumentRequest request)
   at SyncInvokeCheckinDocument(Object , Object[] , Object[] )
   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc)
   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)
   at System.ServiceModel.Dispatcher.ChannelHandler.DispatchAndReleasePump(RequestContext request, Boolean cleanThread, OperationContext currentOperationContext)
   at System.ServiceModel.Dispatcher.ChannelHandler.HandleRequest(RequestContext request, OperationContext currentOperationContext)
   at System.ServiceModel.Dispatcher.ChannelHandler.AsyncMessagePump(IAsyncResult result)
   at System.ServiceModel.Dispatcher.ChannelHandler.OnAsyncReceiveComplete(IAsyncResult result)
   at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
   at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
   at System.Runtime.InputQueue`1.AsyncQueueReader.Set(Item item)
   at System.Runtime.InputQueue`1.EnqueueAndDispatch(Item item, Boolean canDispatchOnThisThread)
   at System.Runtime.InputQueue`1.EnqueueAndDispatch(T item, Action dequeuedCallback, Boolean canDispatchOnThisThread)
   at System.ServiceModel.Channels.SingletonChannelAcceptor`3.Enqueue(QueueItemType item, Action dequeuedCallback, Boolean canDispatchOnThisThread)
   at System.ServiceModel.Channels.HttpPipeline.EnqueueMessageAsyncResult.CompleteParseAndEnqueue(IAsyncResult result)
   at System.ServiceModel.Channels.HttpPipeline.EnqueueMessageAsyncResult.HandleParseIncomingMessage(IAsyncResult result)
   at System.Runtime.AsyncResult.AsyncCompletionWrapperCallback(IAsyncResult result)
   at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
   at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
   at System.ServiceModel.Channels.HttpInput.ParseMessageAsyncResult.OnRead(IAsyncResult result)
   at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
   at System.Web.Hosting.AsyncResultBase.Complete(Int32 hresult, Boolean synchronous)
   at System.Web.Hosting.PipelineRuntime.AsyncCompletionHandler(IntPtr rootedObjectsPointer, Int32 bytesCompleted, Int32 hresult, IntPtr pAsyncCompletionContext)