Thank you for contacting Sitefinity support. Please make sure that you have an unaltered connection string on your dev and live servers. You can check these under ~/App_Data/Sitefinity/Configuration/DataConfig.xml
Using SQL Express you might see something like this:
"Data Source=.\SQLEXPRESS;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Sitefinity.mdf"
If you are using a SQL install database check the connection string and initial catalog. Please also check and confirm that there are no connection strings in your web.config that would be set to the wrong server.
All the best,
the Telerik team
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