Event Log Exception: Data at the root level is invalid. Line 1, position 1. (4271644)

When attempting to open the PMAdmin (AD LDS) site the following error is reported in the browser

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Error in the application.

System error occurred. For more information, view the event log.

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And the corresponding event log entry is

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Result: CriticalError

Info:

Service: QPM.Service.Services.AdminService

Exception: System.Xml.XmlException: Data at the root level is invalid. Line 1, position 1.

   at System.Xml.XmlTextReaderImpl.Throw(Exception e)

   at System.Xml.XmlTextReaderImpl.ParseRootLevelWhitespace()

   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()

   at System.Xml.XmlReader.MoveToContent()

   at System.Xml.Linq.XElement.Load(XmlReader reader, LoadOptions options)

   at System.Xml.Linq.XElement.Parse(String text, LoadOptions options)

   at QPM.Service.Storages.XmlStorage.decryptProtectedChapterXml(XElement xml, XmlStorageProtection protection)

   at QPM.Service.Storages.XmlStorage.Load()

   at QPM.Service.Storages.SharedStorage.Load()

   at QPM.Service.Services.CommonServiceBase.GetTroubleShootingMode()

   at SyncInvokeGetTroubleShootingMode(Object , Object[] , Object[] )

   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)

   at QPM.Service.Infrastructure.LogExceptionsInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)

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Previously there was an instance of standard (Active Directory) Password Manager installed on this server and the shared & local storage files from the old instance were still on the server. When PM ADLDS tried to read these, the exception was thrown.

1. Stop the Password Manager service
2. Remove the following folder and all its contents.

C:\ProgramData\One Identity\Password Manager\

3. Start the Password Manager service
4. Verify that the PMAdmin site can now be opened.