Autofac injects null

I have a very strange problem with Autofac 2.5.2.830 for .NET 3.5: I user builder.RegisterAssemblyTypes to register the types in my assemblies:

builder.RegisterAssemblyTypes("My.*.dll").Where(x => x.Name.EndsWith("Service"))
                                         .AsImplementedInterfaces();

I have several classes that have a dependency on IConfigService. A instance of the concrete implementor of this interface is injected to them but on class gets null injected.

It looks like some sort of a Heisenbug to me, because I can make go it away using breakpoints. However, even this is non-deterministic: Sometimes, the bug goes away, when I set a breakpoint in the class that normally gets the null injected, sometimes the null is injected even with the breakpoint. Setting a break point in one of the classes that are created earlier and also have a dependency on IConfigService leads to an injection of a value instead of n开发者_JAVA百科ull into the problematic class. Even removing a completely unrelated registration from the builder caused the bug to go away once.

However, one thing seems to be constant: It is always the same class that receives the null.

I have no idea where to begin troubleshooting this problem. Is something like this known? What might be the reasons for a null injection?

UPDATE

Oh my, this is stupid...

The constructor looks like this:

public EmailNotifier(IConfigurationService configService)
{
    _mailServerAddress = _configService.Get(Resources.MailServerAddress,
                                            Resources.DefaultSenderAddress);
    _configService = configService;
}

When run, this gave me a NullReferenceException in the first line of the constructor, because _configService was null. It looks like, when I set the breakpoint, I sometimes checked whether configService is null and sometimes whether _configService is null. Because of this it looked like sometimes I got null injected and sometimes not.

SUMMARY

This is NOT a problem with Autofac, because null was never injected. configService always had a value.

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Can you post some code for "the same class that receives the null." - especially the constructor(s)

Can you also confirm that the null can definitely be seen if you put a breakpoint in the constructor - not that it could be some overwritten somewhere later?

My guess is that something is going wrong in the class somewhere.