If you have upgraded your project following the path: 5.2 » 5.4 » 6.0
and Sitefinity upgrade documentation:
Then the problem is in the upgrade process. We would suggest you to upgrade your project again. Please note that after an upgrade to Sitefinity 5.4 you need to run the project (this way the upgrade scripts will be executed). Then perform an upgrade to 6.0.
The other option that you have if you do not want to upgrade your project is to:
1. Open your project in Visual Studio
2. Go to App_Data -> Sitefinity -> Configurations.
3. Open SystemConfig.config file .
4. Change the build from: build="4200" to build="3800"
5. Remove the version (marked part) of the Libraries module:
Then the line should look like this:
Without a version Sitefinity will attempt to reinstall the modules. Then restart the application by making a dummy change in your web.config file and run your project again.
6. Save the file.
7. Go to web.config file, make a dummy change and save the file.
8. Run the project.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items