Simple GET failing with Acumatica API - api

Question

I have been having misc. issues with the Acumatica API where it sometimes works and sometimes throws errors. I decided to drop the db and reinstall my site and start over. After doing this, now I'm just doing a simple login POST and GET of the StockItem endpoint and I get an error (see below). I've tried reinstalling more than once. No customizations are installed.
{
"message": "An error has occurred.",
"exceptionMessage": "Object reference not set to an instance of an object "exceptionType": "System.NullReferenceException",
"stackTrace": " at PX.Data.Process.PXScreenProcessor.HackEtwTrace(Boolean s)\r\n
at PX.Data.Process.PXScreenProcessor.Process(String uri, IPrincipal user, AsyncCallback cb, Action`1 initContext)\r\n
at PX.Api.ScreenUtils.GetScreenInfoWithoutHttpContext(String screenID)\r\n
at PX.Api.ContractBased.EntityExportContextBuilder..ctor(String version, String name, IMetadataProvider metadataProvider, IEntityMappingKeyService entityMappingKeyService, EntityImpl entity, Func`2 screenInfoGetter, ISystemContract systemContract, Boolean returnFullEntities, PXGraph graph) in F:\\Bld2\\AC-FULL2017R204-JOB1\\sources\\NetTools\\PX.Api.ContractBased\\EntityExportContextBuilder.cs:line 73\r\n
at PX.Api.ContractBased.EntityService.GetList(ISystemContract systemContract, String version, String name, EntityImpl entity, Boolean returnFullEntities, CbOperationContext operationContext, Boolean ignoreValueFields, PXGraph graph) in F:\\Bld2\\AC-FULL2017R204-JOB1\\sources\\NetTools\\PX.Api.ContractBased\\EntityService.cs:line 82\r\n
at PX.Api.ContractBased.Soap.SoapFacadeBase.GetListImpl(Entity entity, Boolean returnFullEntities) in F:\\Bld2\\AC-FULL2017R204-JOB1\\sources\\NetTools\\PX.Api.ContractBased\\Soap\\SoapFacadeBase.cs:line 83\r\n
at PX.Api.ContractBased.SystemContracts.V2.RestController.GetList(String objectName, String select, String filter, String expand, String custom, Nullable`1 skip, Nullable`1 top) in F:\\Bld2\\AC-FULL2017R204-JOB1\\sources\\NetTools\\PX.Api.ContractBased\\SystemContracts\\V2\\RestController.cs:line 247\r\n
at lambda_method(Closure , Object , Object[] )\r\n
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)\r\n
at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Web.Http.Controllers.ExceptionFilterResult.<ExecuteAsync>d__0.MoveNext()\r\n
--- End of stack trace from previous location where exception was thrown ---\r\n
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n
at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()"
}
Login:
http://localhost/AcumaticaERP/entity/auth/login
Get:
http://localhost/AcumaticaERP/entity/Default/6.00.001/StockItem
Other endpoints besides StockItem also fail with the same error. I even restarted my PC, but the same error. Any ideas what happened or how to resolve?

Answer 1

This issue is caused by some modification in the .Net Framework library by Microsoft. Once it is installed it is very hard to remove it and will cause problem with certain functionalities in Acumatica. Once Acumatica was made aware of this issue they corrected it so depending on the Acumatica version that you are using it might work or not work.
The version from which the fix was applied to are :
2017R2 : 17.208.0034
2018R1 : 18.102.0048
if you have an account to the Acumatica portal you can even go see the article that was released there :
https://portal.acumatica.com/knowledgebase/known-issue-integrations-schedulers-generic-inquiries-using-odata-may-stop-working-on-2017r2-and-2018r1-versions-after-installing-net-framework-4-7-2-build-or-the-latest-windows-update-which-cont/