SharePoint 2010 - Receiving error attempting to use SPWebConfigModification

Question

I'm creating a SharePoint feature and within my FeatureReceiver I'm attempting to add a SPWebConfigModification. I've been following the approach outlined in this blog post.

Here is a snippet from my feature receiver:

public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
    var webApp = (SPWebApplication)properties.Feature.Parent;

    var debugMode = new SPWebConfigModification
                    {
                        Path = "configuration/system.web/customErrors",
                        Name = "mode",
                        Value = "Off",
                        Sequence = 0,
                        Type = SPWebConfigModification.SPWebConfigModificationType.EnsureAttribute,
                        Owner = "MyWebConfigMods"
                    };

    webApp.WebConfigModifications.Add(debugMode); // <------ Error is thrown at this line
    webApp.WebService.ApplyWebConfigModifications();
    webApp.Update();
}

Here is the stack trace from the error as seen in the SharePoint ULS viewer:

Feature receiver assembly 'MyCompany.SharePoint, Version=1.0.0.0, Culture=neutral, PublicKeyToken=xxxxxxxxxxxxxx', class 'MyCompany.SharePoint.Features.WebConfig.WebConfigFeatureReceiver', method 'FeatureActivated' for feature '3a07b91c-0968-4f14-b2bc-ae0e3f109cf9' threw an exception: System.Xml.XPath.XPathException: '' is an invalid expression.    
at MS.Internal.Xml.XPath.XPathScanner..ctor(String xpathExpr)    
at MS.Internal.Xml.XPath.XPathParser.ParseXPathExpresion(String xpathExpresion)    
at MS.Internal.Xml.XPath.QueryBuilder.Build(String query, Boolean allowVar, Boolean allowKey)    
at System.Xml.XPath.XPathExpression.Compile(String xpath, IXmlNamespaceResolver nsResolver)    
at System.Xml.XPath.XPathNavigator.Select(String xpath)    
at System.Xml.XmlNode.SelectSingleNode(String xpath)    
at Microsoft.SharePoint.Administration.SPWebConfigFileChanges.ApplyModificationsWebConfigXmlDocument(XmlDocument xdWebConfig, String filepath)    
at Microsoft.SharePoint.Administration.SPWebApplication.ApplyWebConfigModifications()    
at Microsoft.SharePoint.Administration.SPWebService.ApplyWebConfigModifications()    
at MyCompany.SharePoint.WebConfigModificationFeatureReceiver.FeatureActivated(SPFeatureReceiverProperties properties)    
at Microsoft.SharePoint.SPFeature.DoActivationCallout(Boolean fActivate, Boolean fForce)

Somewhere during the update an empty path is being referenced within an XPath expression. It's not in my feature. Any ideas?

Answer 1

customErrors does not have an attribute named debug, you must be referring to compilation element

Answer 2

I have similar problem. Any ideas?

Answer 3

This is the code we use:

                SPWebApplication wappCurrent = (SPWebApplication)properties.Feature.Parent;
                SPWebConfigModification modAuthorizedType = new SPWebConfigModification();
                modAuthorizedType.Name = "authorizedType[@Assembly='Infowise.AssociatedTasks, Version=1.0.0.0, Culture=neutral, PublicKeyToken=23853b1f8d5855a5']";
                modAuthorizedType.Owner = "Infowise.Actions";
                modAuthorizedType.Path = "configuration/System.Workflow.ComponentModel.WorkflowCompiler/authorizedTypes";
                modAuthorizedType.Type = SPWebConfigModification.SPWebConfigModificationType.EnsureChildNode;
                modAuthorizedType.Value = @"<authorizedType Assembly=""Infowise.AssociatedTasks, Version=1.0.0.0, Culture=neutral, PublicKeyToken=23853b1f8d5855a5"" Namespace=""Infowise.Sharepoint.V3.Fields.Workflow"" TypeName=""*"" Authorized=""True"" />";
                wappCurrent.WebConfigModifications.Add(modAuthorizedType);
                wappCurrent.Update();
                wappCurrent.Farm.Services.GetValue<SPWebService>().ApplyWebConfigModifications();

Hope if helps