Error Unable to establish a connection to the database when the application is deployed
|Product||Progress® Telerik® Reporting|
The error message
Unable to establish a connection to the database. Please verify that your connection string is valid. In case you use a named connection string from the application configuration file, make sure the name is correct and the connection string settings are present in the configuration file of your application. ------------- InnerException ------------- The 'DbProviderFactories' section can only appear once per config file.
is returned from the attempt to deploy an application to a server.
The issues is caused by multiple DbProviderFactory entries in the machine.config file on the server.
Check the specified configuration files and compare them with development machine's ones. Alternatively, some troubleshooting instructions are discussed in the following stackoverflow threads: