Debugging Error upon creating MySite

In a SharePoint intranet, feature stapling is applied to the standard MySite site definition to customize and extend the newly created employee’s MySite’s. After making some requested changes to the custom MySite masterpage, I deployed the SharePoint solution to the development farm. When validating that upon first visit an employee’s MySite is still successful and correct created, I got a runtime error. The display error message gave no details on the problem cause, and in the 12hive log no related information was found. Due a lack of rights to open the EventLog on the remote development server, I could not [myself] check whether in there useful logging was available.

So, what to do? Due the nature of my changes I was pretty sure that the malfunction could not be related back to them. But pretty sure is not good enough, when the ultimate deployment target is the company production intranet. I needed to exactly pinpoint the problem cause, and proof that it was not related to my deployment.

The SharePoint standard MySite creation handling hides the details of the thrown and catched exceptions. To detect what exception was thrown, I therefore created my own DebugMySite.aspx, and filled it with the basics of the standard MySite creation handling – with the noticeable difference to expose the exception details within the browser. Via this debugging approach I learned that the internal error message reported the following:

My Site creation failure for user '<domain>\<username>' for site url 'https://SharePointServer/personal/<username>'. The exception was:
Microsoft.Office.Server.UserProfiles.PersonalSiteCreateException: There has been an error creating the personal site ---> System.ArgumentException: Value does not fall within the expected range.
at Microsoft.SharePoint.Library.SPRequestInternalClass.SscCreateSite(Guid gApplicationId, String bstrUrl, String bstrServerRelativeUrl, Int32 lZone, Guid gSiteId, Guid gDatabaseId, String bstrDatabaseServer, String bstrDatabaseName, String bstrDatabaseUsername, String bstrDatabasePassword, String bstrTitle, String bstrDescription, UInt32 nLCID, String bstrWebTemplate, String bstrOwnerLogin, String bstrOwnerUserKey, String bstrOwnerName, String bstrOwnerEmail, String bstrSecondaryContactLogin, String bstrSecondaryContactUserKey, String bstrSecondaryContactName, String bstrSecondaryContactEmail, Boolean bADAccountMode)
at Microsoft.SharePoint.Library.SPRequest.SscCreateSite(Guid gApplicationId, String bstrUrl, String bstrServerRelativeUrl, Int32 lZone, Guid gSiteId, Guid gDatabaseId, String bstrDatabaseServer, String bstrDatabaseName, String bstrDatabaseUsername, String bstrDatabasePassword, String bstrTitle, String bstrDescription, UInt32 nLCID, String bstrWebTemplate, String bstrOwnerLogin, String bstrOwnerUserKey, String bstrOwnerName, String bstrOwnerEmail, String bstrSecondaryContactLogin, String bstrSecondaryContactUserKey, String bstrSecondaryContactName, String bstrSecondaryContactEmail, Boolean bADAccountMode)
at Microsoft.SharePoint.Administration.SPSiteCollection.Add(SPContentDatabase database, String siteUrl, String title, String description, UInt32 nLCID, String webTemplate, String ownerLogin, String ownerName, String ownerEmail, String secondaryContactLogin, String secondaryContactName, String secondaryContactEmail, String quotaTemplate, String sscRootWebUrl, Boolean useHostHeaderAsSiteName)
at Microsoft.SharePoint.SPSite.SelfServiceCreateSite(String siteUrl, String title, String description, UInt32 nLCID, String webTemplate, String ownerLogin, String ownerName, String ownerEmail, String contactLogin, String contactName, String contactEmail, String quotaTemplate)

With these error details, I could do a focussed search on the internet. And found this related forum-entry Error creating MySite: There has been an error creating the personal site, which had the answer: "add the account configured as the Application Pool Identity for the web site to the "Farm Administrators" group through the Central Administration pages". This was the situation earlier for the intranet webapplication on our development farm, but somehow this got broken. With this knowledge I went to our IT pro, and asked them to restate the AppPool identity as a farm admin, followed by an IISReset. After that, the MySite creation problem was solved.