System.Data Assembly Not found

Question

I have a reference to System.Data in my windows service project. I keep getting the Exception :

Could not load file or assembly 'System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The system cannot find the file specified.

I attach the FusionLog to my code and found out the following. For System.Data only visual studio is looking here:

Assembly manager loaded from: C:\windows\Microsoft.NET\Framework\v2.0.50727\mscorwks.dll

And it should be looking here (all the other assemblies are but System.Data)

Assembly manager loaded from: C:\windows\Microsoft.NET\Framework\v4.0.30319\clr.dll

How can I do point my System.Data file to look in the right place?

My guess is Microsoft Commerce Server dlls are referenceing the 2.0 folder maybe.

score 5 · Accepted Answer · answered May 22 '12 at 13:52

5

Add this to app.config..

  <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0" />
  </startup>

If you need old versions of dlls to be loaded in a windows service you must add this. For web services iis automatically takes care of it, but not for windows service.

answered May 22 '12 at 13:52

Nick LaMarca

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I have the same problem with my .Net 3.5 project, even had above useLegacyV2RuntimeActivationPolicy added. But I can still observe "System.Data not found" exception in Visual Studio output window as first chance exception when debug run. However, except for this, my application runs OK. – neolei Feb 14 '20 at 04:44

score 2 · Answer 2 · answered May 17 '12 at 19:08

2

Make sure your project is set to .Net Framework 4. If that doesn't do it, set it to full profile (not just Client)

answered May 17 '12 at 19:08

Otávio Décio

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@NickLaMarca Is the full framework installed on the client then? – Oskar Kjellin May 17 '12 at 19:24
Sanity check - can you find the file C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.Data.dll ? – Otávio Décio May 17 '12 at 19:26
The folder v4.0.30319 is installed on my machine – Nick LaMarca May 17 '12 at 19:30
Yes I see System.Data.dll here: C:\Program Files\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0 – Nick LaMarca May 17 '12 at 19:32
Do you have in your web.config? – Otávio Décio May 17 '12 at 19:35
I have this in my app.config – Nick LaMarca May 17 '12 at 19:37
Just curious - are you passing DataSets around through you web service? – Otávio Décio May 17 '12 at 19:39
this is a windows service and yes I am calling datasets then mapping them to an object – Nick LaMarca May 17 '12 at 19:41
That could be your problem, if your client is 2.0 and your server 4.0 – Otávio Décio May 17 '12 at 19:42
4.0 is installed on server and client – Nick LaMarca May 17 '12 at 19:45

score 2 · Answer 3 · answered May 21 '12 at 14:52

2

If you select the referenced assembly in the solution explorer, verify that the runtime version is correct (see image below). You can remove the reference and re-add it to fix it if necessary.

Also, if you are using an app.config, make sure it is targeting the correct runtime version.

enter image description here

answered May 21 '12 at 14:52

BryanJ

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I verified all System.Data dlls in all projects in the solution have the 4.0 runtime version and the app config is targeting 4.0 – Nick LaMarca May 21 '12 at 14:53

System.Data Assembly Not found

3 Answers3

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