This issue was reported via Connect http://connect.microsoft.com/VisualStudio/feedback/details/761883/vs-give-unknown-error-message-while-generating-db-from-ef
The Connect issue records that a few different folks have hit this problem. We haven't been able to reproduce it but it seems like the steps are:
1. Create a model that targets a non-SQL Server database using VS2010
1. Upgrade to VS2012
1. Select 'Generate database from model...'
The result is an error:
```
---------------------------
Microsoft Visual Studio
---------------------------
An exception of type 'Microsoft.VSDesigner.Data.Local.ConnectionStringConverterServiceException' occurred while attempting to generate the database script from the model. The exception message is: ''.
---------------------------
ОК
---------------------------
```
We definitely need to fix the error message (note the empty string at the end of the message). It looks like ConnectionStringConverterServiceException is owned by another team at Microsoft so we will probably need their help.
If we are able to reproduce the issue we also need to understand why the connection string is becoming invalid.
Here are some notes on a workaround provided by Lawrence:
> The error is coming from not being able to interpret the connection string. We don't own the module that does that but from reading the forums it looks like this can often happen if the provider is not properly installed. So if you are upgrading VS make sure you re-install your provider. Once that's done, as an easy workaround, comment out the relevant connection string in your app or web.config. Then go through "Update Model from Database" (selecting nothing new if that's what you want). When it detects that there is no connection string associated with the model it will offer you the page where you get to choose which connection to use. Select your connection and a new connection string with the appropriate format should be put in your .config file.
The Connect issue records that a few different folks have hit this problem. We haven't been able to reproduce it but it seems like the steps are:
1. Create a model that targets a non-SQL Server database using VS2010
1. Upgrade to VS2012
1. Select 'Generate database from model...'
The result is an error:
```
---------------------------
Microsoft Visual Studio
---------------------------
An exception of type 'Microsoft.VSDesigner.Data.Local.ConnectionStringConverterServiceException' occurred while attempting to generate the database script from the model. The exception message is: ''.
---------------------------
ОК
---------------------------
```
We definitely need to fix the error message (note the empty string at the end of the message). It looks like ConnectionStringConverterServiceException is owned by another team at Microsoft so we will probably need their help.
If we are able to reproduce the issue we also need to understand why the connection string is becoming invalid.
Here are some notes on a workaround provided by Lawrence:
> The error is coming from not being able to interpret the connection string. We don't own the module that does that but from reading the forums it looks like this can often happen if the provider is not properly installed. So if you are upgrading VS make sure you re-install your provider. Once that's done, as an easy workaround, comment out the relevant connection string in your app or web.config. Then go through "Update Model from Database" (selecting nothing new if that's what you want). When it detects that there is no connection string associated with the model it will offer you the page where you get to choose which connection to use. Select your connection and a new connection string with the appropriate format should be put in your .config file.