SharePoint error: "Cannot import Web Part"

Question

I have a web part that I've developed, and if I manually install the web part it is fine.

However when I have packaged the web part following the instructions on this web site as a guide: http://www.theartofsharepoint.com/2007/05/how-to-build-solution-pack-wsp.html

I get this error in the log files:

09/23/2008 14:13:03.67  w3wp.exe (0x1B5C)                           0x1534  Windows SharePoint Services     Web Parts                       8l4d    Monitorable Error importing WebPart. Cannot import Project Filter.   
09/23/2008 14:13:03.67  w3wp.exe (0x1B5C)                           0x1534  Windows SharePoint Services     Web Parts                       89ku    High        Failed to add webpart http%253A%252F%252Fuk64p12%252FPWA%252F%255Fcatalogs%252Fwp%252FProjectFilter%252Ewebpart;Project%2520Filter.  Exception Microsoft.SharePoint.WebPartPages.WebPartPageUserException: Cannot import Project Filter.     at Microsoft.SharePoint.WebPartPages.WebPartImporter.CreateWebPart(Boolean clearConnections)     at Microsoft.SharePoint.WebPartPages.WebPartImporter.Import(SPWebPartManager manager, XmlReader reader, Boolean clearConnections, Uri webPartPageUri, SPWeb spWeb)     at Microsoft.SharePoint.WebPartPages.WebPartImporter.Import(SPWebPartManager manager, XmlReader reader, Boolean clearConnections, SPWeb spWeb)     at Microsoft.SharePoint.WebPartPages.WebPartQuickAdd.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(...  
09/23/2008 14:13:03.67* w3wp.exe (0x1B5C)                           0x1534  Windows SharePoint Services     Web Parts                       89ku    High        ...String eventArgument)     

The pertinent bit is:

http%253A%252F%252Fuk64p12%252FPWA%252F%255Fcatalogs%252Fwp%252FProjectFilter%252Ewebpart;Project%2520Filter.
Exception Microsoft.SharePoint.WebPartPages.WebPartPageUserException: Cannot import Project Filter.
at Microsoft.SharePoint.WebPartPages.WebPartImporter.CreateWebPart(Boolean clearConnections)
at Microsoft.SharePoint.WebPartPages.WebPartImporter.Import(SPWebPartManager manager, XmlReader reader, Boolean clearConnections, Uri webPartPageUri, SPWeb spWeb)
at Microsoft.SharePoint.WebPartPages.WebPartImporter.Import(SPWebPartManager manager, XmlReader reader, Boolean clearConnections, SPWeb spWeb)
at Microsoft.SharePoint.WebPartPages.WebPartQuickAdd.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)

And that's accompanied by a rather terse error message: "Cannot import web part".

I have checked and my .dll is registered as safe, it is in the GAC, the feature is activated, and the web parts appear in the web part library with all of the correct properties showing that the webpart files were read successfully.

Everything appears to be in place, yet I get that error and little explanation from SharePoint of how to resolve it.

Any help finding a solution is appreciated.

Answer 1

Figured it out.

The error message is the one from the .webpart file:

<?xml version="1.0" encoding="utf-8"?>
<webParts>
  <webPart xmlns="http://schemas.microsoft.com/WebPart/v3">
    <metaData>
      <!--
      The following Guid is used as a reference to the web part class, 
      and it will be automatically replaced with actual type name at deployment time.
      -->
      <type name="7F8C4D34-6311-4f22-87B4-A221FA8735BA" />
      <importErrorMessage>Cannot import Project Filter.</importErrorMessage>
    </metaData>
    <data>
      <properties>
        <property name="Title" type="string">Project Filter</property>
        <property name="Description" type="string">Provides a list of Projects that can be used to Filter other Web Parts.</property>
      </properties>
    </data>
  </webPart>
</webParts>

The problem is that the original .webpart file was created on a 32-bit system with Visual Studio Extensions for WSS installed.

However as I'm now on a 64-bit machine VSEWSS is unavailable, and I believe that results in the above GUID not being substituted as I am not using those deployment tools.

Replacing the GUID with the full type name works.

So if you encounter the error message from your importErrorMessage node, then check that your type node in the .webpart file looks more like this (unrelated example):

<type name="TitleWP.TitleWP, TitleWP, Version=1.0.0.0, Culture=neutral, PublicKeyToken=9f4da00116c38ec5" />

This is in the format: Class, Namespace, Version, Culture, PublicKey

You can grab that easily from the web.config file associated with your SharePoint instance, as it will be in the safe controls list.