Thursday, August 30, 2012

How to fix “An error occurred when starting printer spooler.” when you start Muhimbi Dcocument Convertor Service?

The Muhimbi PDF Converter for SharePoint allows end-users to convert, split, merge and secure common document types such as MS-Word, InfoPath, MSG (email), AutoCAD, Excel, HTML, PowerPoint, Publisher, Visio, ODF, TIFF, JPG and PNG from within SharePoint using a friendly interface, custom Nintex and SharePoint Designer workflows or even a Web Service call. The product also comes with powerful watermarking and PDF merging engines.

One of the Muhimbi components is window service Document Convertor Service that will convert documents into different format such as PDF. During the installation for this component, you might run into one issue to this service will fail to start due to the following error – “An error occurred when starting printer spooler.” as in the following screen shot. When we try to manually start the Print Spooler service, we got error also.

Here is the reason and solution to fix the issue. The Muhimbi Document Convertor Service depends on the Print Spooler to convert document to different formats. If Print Spooler not started, Muhimbi Document Convertor Service will NOT start. As a result, the key to resolve this is to make sure start Print Spooler service. The root cause not be able to start the Print Spooler is the corrupted
registration information for HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ Spooler. The value should ONLY contain value RPCSS. But you will see other values such as http is there.

You could manually remove other values and just leave RPCSS there. I would prefer to use the following command posted by David Vinod to resolve this issue.

Click Start, Run and type the following:

You should retsrat the phisical server after registry change. Now, you should be able to start Muhimbi Document Convertor Service and enjoy document conversion to PDF on SharePoint.

Tuesday, August 28, 2012

Tips to resolve “Unable to Refresh the Excel Connection in Excel Webaccess Webpart” in SharePoint 2010

Aftwe users start to use excel service on SharePoint 2010, we have encoutered many issues. One os the top issues is users could not refresh excel workbook and got “Unable to Refresh the Excel Connection in Excel Webaccess Webpart”. 

As you might not know that all authentication and communication inside SharePoint is through claim. Any SharePoint service that relies on the Claims to Windows token service (C2WTS) must use Kerberos constrained delegation to allow the C2WTS to use Kerberos protocol transition to translate claims into Windows credentials. Excel Services along with PerformancePoint Services and Visio Services are the three service applications and products require the C2WTS and Kerberos constrained delegation.
In most cases, we will need to configure the SharePoint Server Excel Services service account for Kerberos constrained delegation to the SQL Server service. You may use security store also. The scenario is detailed in the following screen shot as explained in Microsoft forum.

Authentication in this scenario begins with the client authenticating with Kerberos authentication at the web front end. SharePoint Server 2010 will convert the Windows authentication token into a claims token using the local Security Token Service (STS). The excel service application will accept the claims token and convert it into a windows token (Kerberos) using the local Claims to Windows Token Service (C2WTS) that is a part of Windows Identity Framework (WIF). The excel service application will then use the client’s Kerberos ticket to authenticate with the backend DataSource.

At this point, you might be clear that we need to set up the following three setting in order to make excel refresh work.
  1. Enable Kerberos on the webapp to delegate user account
  2. Start C2WTS on the farm to transition to translate claims into Windows credentials
  3. Add Trusted Data Connection Libraries for connection files and Trusted File Location for excel file
Yes, you have to have all THREE configured correctly in order to resolve this issue. You could refer to Microsoft plan and instruction to set up Kerberos for excel service.