Problem when running Azure function locally using Azure Functions Core Tools

Question

I am developing a durable Azure function. I am using .NET Core 3.1. It is an HTTP-triggered function. When I debug it from Visual Studio and then trigger it by calling the endpoint everything works.

On the same machine I installed Azure Functions Core Tools (4.0.3971). I run the storage emulator:

C:\Program Files (x86)\Microsoft SDKs\Azure\Storage Emulator\AzureStorageEmulator.exe start

Then go to the directory where my function resides and type:

func start

Everything works the same as previously, so I trigger my function by making a request to the endpoint. It starts doing its work, but then throws the following error:

[2021-12-03T14:25:51.081Z] Executed 'MyFunction_Process' (Failed, Id=f709e4c0-f74e-4303-a68b-6d5d55f0f7e5, Duration=2182ms)
[2021-12-03T14:25:51.086Z] System.Private.CoreLib: Exception while executing function: MyFunctionIntegration_Process. Microsoft.EntityFrameworkCore: The type initializer for 'Microsoft.EntityFrameworkCore.EnumerableMethods' threw an exception. System.Linq: Sequence contains more than one matching element.
[2021-12-03T14:25:51.101Z] myfunctionsingleinstance: Function 'MyFunction_Process (Activity)' failed with an error. Reason: System.TypeInitializationException: The type initializer for 'Microsoft.EntityFrameworkCore.EnumerableMethods' threw an exception.
[2021-12-03T14:25:51.106Z]  ---> System.InvalidOperationException: Sequence contains more than one matching element
[2021-12-03T14:25:51.110Z]    at System.Linq.ThrowHelper.ThrowMoreThanOneMatchException()
[2021-12-03T14:25:51.112Z]    at System.Linq.Enumerable.TryGetSingle[TSource](IEnumerable`1 source, Func`2 predicate, Boolean& found)
[2021-12-03T14:25:51.113Z]    at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
[2021-12-03T14:25:51.115Z]    at Microsoft.EntityFrameworkCore.EnumerableMethods..cctor()
[2021-12-03T14:25:51.116Z]    --- End of inner exception stack trace ---
[2021-12-03T14:25:51.117Z]    at Microsoft.EntityFrameworkCore.EnumerableMethods.get_AnyWithPredicate()
[2021-12-03T14:25:51.119Z]    at Microsoft.EntityFrameworkCore.Query.Internal.AllAnyToContainsRewritingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
[2021-12-03T14:25:51.121Z]    at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
[2021-12-03T14:25:51.124Z]    at Microsoft.EntityFrameworkCore.Query.QueryTranslationPreprocessor.Process(Expression query)
[2021-12-03T14:25:51.126Z]    at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
[2021-12-03T14:25:51.128Z]    at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
[2021-12-03T14:25:51.129Z]    at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
[2021-12-03T14:25:51.131Z]    at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass9_0`1.<Execute>b__0()
[2021-12-03T14:25:51.133Z]    at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
[2021-12-03T14:25:51.134Z]    at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
[2021-12-03T14:25:51.136Z]    at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
[2021-12-03T14:25:51.140Z]    at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
[2021-12-03T14:25:51.141Z]    at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetEnumerator()
[2021-12-03T14:25:51.143Z]    at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.IncludableQueryable`2.GetEnumerator()
[2021-12-03T14:25:51.144Z]    at System.Linq.Enumerable.ToDictionary[TSource,TKey](IEnumerable`1 source, Func`2 keySelector, IEqualityComparer`1 comparer)
[2021-12-03T14:25:51.146Z]    at System.Linq.Enumerable.ToDictionary[TSource,TKey](IEnumerable`1 source, Func`2 keySelector)
[2021-12-03T14:25:51.148Z]    at Logistics.Infrastructure.MyFunctionIntegration.Integration.GetDbRows(ILogger log) in C:\Users\Michal\source\repos\Logistics\src\backend\src\infrastructure\Logistics.Infrastructure.MyFunctionIntegration\Integration.cs:line 103
...

The line 103 is:

var dbEntities = _dbContext.Carriers.IgnoreQueryFilters().Include(c => c.CarrierGitd.Address).ToDictionary(c => c.CarrierGitd?.LicenseNumber);

So it happens when I try to fetch data from the database. But it works fine, when I debug in VS. The database is the same. Where's the catch?

Answer 1

I needed to support both a v3 and v4 functions project so I just took a copy of the V3 tools directory C:\Program Files\Microsoft\Azure Functions Core Tools (then named it something like 'Azure Functions Core Tools v3'), installed V4 and created a batch file to run the correct 'func.exe' in the directory for the old v3 project.

Answer 2

The problem went away when I upgraded Microsoft.EntityFrameworkCore to 5.0.0 in SecondLib dependency.

<ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.NetTopologySuite" Version="5.0.0" />
  </ItemGroup>

The TargetFramework wasn't touched

<TargetFramework>netcoreapp3.1</TargetFramework>
<AzureFunctionsVersion>v3</AzureFunctionsVersion>

Note:

I got the same issue in the Azure Functions core tools version 3. If your Entity framework core version is < 5.x in second lib dependency, upgrade and try once. Or If possible, downgrade Azure Functions Core tools version to 3 and check.