Cannot add webpart to page - DLL not registered in Assembly

Question

Background:

I have developed a Farm solution webpart for SharePoint 2013 Enterprise more than a year ago. This project uses two DLL which are:

• sample_1.dll
• sample_2.dll

The whole solution consist:

• (2) Class libraries build in Framework 4.0 (for use the SharePoint Dll's reference described below).
• SharePoint 2013 visual webpart.

These DLL's uses the following SharePoint DLL reference:

• Microsoft.SharePoint.dll: "runtime version used is v4.0.30319 / version 15.0.0.0".

These DLL's are registered in the PC that I used for develop this project and the project itself was implemented in a test site.

Due to certain limitations that I'm afraid I can't explain in detail, the Application pool and the site "in IIS" was shutdown after delivery this project to the client (mostly for saving "RAM")...

Now, the site and application pool has been turned on again. To my surprise, the site hasn't the webpart anymore and I had to start the implementation again.

Problem:

When I tried to add the webpart in a test page in the test site, I get this error:

Checking the logs, I found this detailed error:

Getting Error Message for Exception Microsoft.SharePoint.WebPartPages.WebPartPageUserException: $Resources:core,ImportErrorMessage; ---> System.Reflection.TargetInvocationException: An exception occurred in the target of an invocation ---> System.IO.FileNotFoundException: Could not load file or assembly 'sample_1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=f1cd0442b97c7541' or one of its dependencies. The system cannot find the file specified.

The web.config file has added the entries in the entries in SafeControls tag.

I have used gacutil.exe for register those DLL's, but, they aren't registered in the following location:

1. C\Windows\assembly

Instead, they're registered in

2. C:\Windows\Microsoft.NET\assembly\GAC_MSIL\sample_1

Which, according to this link I used the 4.0 version of gacutil.exe I should use the 2.0 version.

I really don't understand why these DLL's need to be in the first location.

Answer 1

should be simple enough, could be the issue that the project when deploying is ignoring the dll files. you could set the DLL's to local within VS that adds it to the bin folder or the correct method is that its not stated within the package.package which is simple enough:

1) Open Package.package in visual studios.

2) Click Advanced in bottom area (current view is Design).

3) Click Add and chose the two assemblies you wanted to add/update.

4) Within the dialog select dll file as you need to navigate to where the dll is located, add safe control for both and class resources entries if needed. once complete click the ok button and build then deploy.

now when you deploy to live or any other the two dll's are always deployed every time!

---

also like to note that "C:\Windows\assembly" was pre sharepoint 2013 for .net 3.5 and lower.

in sharepoint 2013+ it uses the new location as you referenced. its slightly different. If you were to build .net 4.0 project it will deploy it to specific folders related the the .net version.

if the two DLL's are 3.5 and lower then they need to be in the older assembly folder "C:\Windows\assembly" using the gacutil.exe.

If the two dlls are 4.0+ then use the newer gacutil.exe located at "\Program Files\Microsoft SDKs\Windows\v7.1\Bin"

in your case you shouldnt need to do above if its properly included in the project, when you deploy it should add them correctly.

also make sure the safe control is correct, check that the key in gac is the same in the safe control.

Answer 2

First check the solution (wsp) is still available on the Farm. If yes then do a deployment and that can fix the dll issues.

To answer your last question, SP 2010 required .Net 3.5 and it will not work with .Net 4.0

Answer 3

This might occur because of assembly 'sample_1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=f1cd0442b97c7541' or one of its dependencies entry has been removed from SharePoint Web APplication web.config file.

To overcome this issue

• Try to retract and redeploy the solution again . (Redeploy process will let you solve the missing entry in web.config by installing your solution again and register DLL to GAC)
• Also, If you have already added a reference to an external DDL's like ajax to your solution make sure that it has already manually located at C:\inetpub\wwwroot\wss\VirtualDirectories\80\bin (change port based on your web application)