Corrupted upgrade 4.0 -> 4.1 SP2

Greetings,
we're facing some problems after upgrading from 4.0 to 4.1 SP2.
We installed the new version of the project manager and after launching the upgrade process without errors, when trying to open the administration pages we get the following error. It seems the upgrade process fails to update config files. Furthermore when we mirror the config from a 4.1 SP2 fresh installation we are able to access the administration area with some tricks on resetting the admin password, but most of the features are malfunctioning giving hints about the fact that dabatase upgrade process failed as well.
At this point we're lost, we cannot guess how to fix the database to the new structure, and we fear we cannot upgrade the production installation and stay still with an outdated product (also not bugfree I should say).

I really hope someone could share a hand.

Regards

Server Error in '/XxxXxxx' Application.
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Invalid property name "profileProviders" for configuration element "SecurityConfig".
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: Invalid property name "profileProviders" for configuration element "SecurityConfig".

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. 

Stack Trace:

[ArgumentException: Invalid property name "profileProviders" for configuration element "SecurityConfig".]
   Telerik.Sitefinity.Abstractions.Exceptions.HandleException(Exception exceptionToHandle, ExceptionPolicyName policy, Exception& exceptionToThrow) +239
   Telerik.Sitefinity.Abstractions.Exceptions.HandleException(Exception exceptionToHandle, ExceptionPolicyName policy) +23
   Telerik.Sitefinity.Configuration.Data.XmlConfigProvider.LoadSectionFromReader(ConfigSection section, XmlReader reader, ConfigPolicyHandler policyHandler, String policyName, Boolean checkForUpgrade, UpgradingInfo& upgradingInfo) +542
   Telerik.Sitefinity.Configuration.Data.XmlConfigProvider.LoadSectionFromFile(ConfigSection section, ConfigPolicyHandler policyHandler, String policyName, Boolean withUpgrade) +138
   Telerik.Sitefinity.Configuration.Data.XmlConfigProvider.LoadSection(ConfigSection section, ConfigPolicyHandler policyHandler, String policyName) +82
   Telerik.Sitefinity.Configuration.ConfigSection.Initialize(ConfigProvider provider, ConfigPolicyHandler policyHandler, String policyName, Boolean singlePolicy) +193
   Telerik.Sitefinity.Configuration.ConfigSection.Initialize(ConfigProvider provider) +30
   Telerik.Sitefinity.Configuration.Config.Get(Boolean safeMode) +272
   Telerik.Sitefinity.Security.SecurityManager..cctor() +202

[TypeInitializationException: The type initializer for 'Telerik.Sitefinity.Security.SecurityManager' threw an exception.]
   Telerik.Sitefinity.Abstractions.Exceptions.HandleException(Exception exceptionToHandle, ExceptionPolicyName policy, Exception& exceptionToThrow) +239
   Telerik.Sitefinity.Abstractions.Exceptions.HandleException(Exception exceptionToHandle, ExceptionPolicyName policy) +23
   Telerik.Sitefinity.Data.ManagerBase`1.Initialize() +773
   Telerik.Sitefinity.Data.ManagerBase`1..ctor(String providerName, String transactionName) +34
   Telerik.Sitefinity.Localization.Res..cctor() +28

[TypeInitializationException: The type initializer for 'Telerik.Sitefinity.Localization.Res' threw an exception.]
   Telerik.Sitefinity.Localization.Res.RegisterResource() +0
   Telerik.Sitefinity.Abstractions.ObjectFactory.RegisterStringResources() +108
   Telerik.Sitefinity.Abstractions.ObjectFactory.RegisterIoCTypes() +206
   Telerik.Sitefinity.Abstractions.Bootstrapper.Bootstrap() +219
   Telerik.Sitefinity.Web.SitefinityHttpModule.Init(HttpApplication context) +114
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +546
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +325
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +407
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +375

[HttpException (0x80004005): The type initializer for 'Telerik.Sitefinity.Localization.Res' threw an exception.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11529072
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4784373

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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1

Hi Simone Cingolani,

Upgrade from 4.0 to 4.1 SP2 is not supported. You have to first upgrade to the official version to 4.1 and then upgrade to the service pack. We always support upgrades for the latest 2 versions, thus in your case it means that if you want to upgrade to 4.1 SP2 you can either do it from 4.1 or 4.1 SP1.

Please let me know if there is anything else we can assist you with. Thank you for contacting us.

All the best,
Hristo Borisov
the Telerik team

Ok we tryed upgrading from 4.0 to official 4.1 build, still no luck.
An empty project upgrades without issues, but ours seems to have lot of issues, to name some:
- duplicate key while updating schema versions
- unable to login with admin credentials
- outdated references version
- duplicate item in config files (i.e. taxonomy)
- and many others

We're developers, so we try to fix everything we can, but still a commercial product should be supported a little more, we paid for a license we cannot use.
Please help us by providing a correct strategy to upgrade in a way or another, or we could also have some of your team upgrade our version.

Best regards

Hi Simone Cingolani,

Send us your project along with the database and we will try to upgrade your project as soon as possible.

All the best,
Hristo Borisov
the Telerik team