The upgrade wizard fails with an XML error when trying to upgrade a project

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Last Updated: 10 Feb 2026 06:48 by Hakon

Hakon

Created on: 21 Jan 2026 09:51

Category: Installer and VS Extensions

Type: Bug Report

The upgrade wizard fails with an XML error when trying to upgrade a project

We have a WebForms application with Telerik AJAX components which we have successfully upgraded using the wizard for years. Starting with product version 2025.4.1210 and persisting in the latest version, 2025.4.1321, the upgrade wizard fails with the following error message.

The Telerik extension to VS is up to date, and it doesn't seem to help to run this in VS 2022.

An error occurred while running the wizard.

Error executing custom action Telerik.Web.UI.VSX.Actions.MultiProjectUpdateReferencesAction: System.InvalidOperationException: There is an error in XML document (3, 2). ---> System.Xml.XmlException: Name cannot begin with the '<' character, hexadecimal value 0x3C. Line 3, position 2.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseQName(Boolean isQName, Int32 startOffset, Int32& colonPos)
   at System.Xml.XmlTextReaderImpl.ParseElement()
   at System.Xml.XmlTextReaderImpl.ParseElementContent()
   at System.Xml.XmlReader.ReadStartElement()
   at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderSolutionDistributionDefinition.Read2_SolutionDistributionDefinition(Boolean isNullable, Boolean checkType)
   at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderSolutionDistributionDefinition.Read3_Distribution()
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
   at System.Xml.Serialization.XmlSerializer.Deserialize(TextReader textReader)
   at Telerik.VSX.Helpers.Serializer`1.Deserialize(String filePath)
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.<>c__DisplayClass11_0.<DeserializeSolutionDistributionDefinition>b__0()
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.HandleUnauthorizedAccessException(Action action)
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.DeserializeSolutionDistributionDefinition(String distributionFilePath)
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.<>c__DisplayClass10_0.<CreateSolutionDistribution>b__0()
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.HandleUnauthorizedAccessException(Action action)
   at Telerik.VSX.SolutionManagement.SolutionDistributionOperator.CreateSolutionDistribution(String distributionFilePath, DistributionInfo distributionInfo)
   at Telerik.VSX.SolutionManagement.SolutionDistributionsContext.LoadSolutionDistributionDefinitions(DistributionInfo distributionInfo)
   at Telerik.VSX.Actions.MultiProjectUpdateReferencesActionBase`1.CreateSolutionDistributionsContext(WizardContext context)
   at Telerik.VSX.Actions.MultiProjectUpdateReferencesActionBase`1.Execute(WizardContext wizardContext, IPropertyDataDictionary arguments)
   at Telerik.VSX.WizardEngine.ActionManager.ExecActions()

2 comments

Hakon

Posted on: 10 Feb 2026 06:48

Maria, thank you for your answer!

I must admit that I don't know where the extension directory resides, nor the name of the "internal XML" file. I would suspect this file is internal to the upgrade package with the new version of the Telerik components, so a hint of what file name to search for, would be most welcome.

ADMIN

Maria

Posted on: 26 Jan 2026 14:19

Hello Hacon,

Thank you for the information.

The error that you are encountering during the upgrade process occurs when our upgrade wizard attempts to deserialize an internal XML containing the distribution information used by the Visual Studio extension. To try to resolve this, please follow the steps below:

1. Check if the XML file exists in the extension directory.
2. Verify that the file is a valid XML, and that it is saved with UTF-8 encoding.
3. If the file exists and is valid, try uninstalling and reinstalling the extension.

If the error still occurs after reinstalling the extension, the XML file may be corrupted or incompatible. You can attach the file to review its contents.

If the issue persists even after following the above steps, please don’t hesitate to contact us again to assist further.

Regards,
Maria
Progress Telerik

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