Report DataSource Wizard throws the InvalidCastException on an attempt to connect to the MySQL database

This fixed the issue, but there is another issue I am having that existed in 15.1.6 but was fixed in 15.1.7 but now returned with the hotfix.  When I click on the query builder button in the wizard I get an 'Unhandled type encountered' exception.  I created 2 videos to show the issue.  The first (attached to this comment) is 15.1.7 before the hotfix.

This video is after the hotfix was applied…

Hi Joe,
I wasn't able to reproduce the described behavior under the provided hotfix. Would you please clarify the exact version of our components you're using? You can do this by running your application via MS Visual Studio and checking the list of loaded assemblies by using the Modules window (Debug -> Windows -> Modules).
Also, you mentioned you were facing exactly the same problem in version 15.1.6, but I didn't recall any similar reported issues. Wold you mind providing me with a link to the related bug report? It would also be great if you can attach the debugger to the target process, and clarify the exception's additional info. Of course, any sample MySQL database we can use for our tests will be appreciated as well (it's the database schema that is important, you can fill it with dummy data).
I'm looking forward to your reply.

I am using the hotfix version 15.01.7.15281.  It doesn't happen with every database.  I think there is a type being used in our DB that your components do not like.  If I choose the MySQL db, the query builder loads.  I tried to search your source code to see where that exception is being thrown, but I couldn't.  I didn't report it previously because I just figured it was something in our DB, but then it worked with 15.01.7 prior to applying the hotfix.  Is there something I can do to better troubleshoot what is causing the exception?

>>  I tried to search your source code to see where that exception is being thrown, but I couldn't.
That's because the exception is thrown by the ADO.NET driver v6.6.4 for MySQL, not by our code. Since you mentioned that "it doesn't happen with every database", I have some good reason to suspect that one or more MySQL types used in your database failed to be mapped to the corresponding CLR types.

>>  Is there something I can do to better troubleshoot what is causing the exception?
I believe it makes sense to run Visual Studio with the disabled optimization (see the detailed instructions here) and set a new breakpoint for the 'NameToType' method. The first parameter of this method is the type actually trying to be converted (see the Debug->Windows->Locals window), so it should give you a clear understanding of what particular DB type throws the exception.
I'm looking forward to your results.

Can you tell me what project the NameToType method is in?  The only one I found was in Utils.UI and the breakpoint is not being hit.

As I already said, the exception is thrown by the MySQL provider (see MetaData.cs), not by our code. If you have the 'Enable just my code' option disabled (Debug -> Options -> Debugging | General), the debugger should be able to resolve a breakpoint by the function name (even if you don't have the source code available). I should note though that according to the GitHub repository, the aforementioned exception is thrown if only a stored procedure is selected, but you're just pressing the 'Query Builder' button to view the available tables. Thus, I'm not certain if that's the same method that causes the exception and it'd be better to just enable the first chance exceptions for the first time ( Debug->Exceptions->CLR Exceptions)

It is caused by stored procs.  I was able to get past that error by correcting some of our types on the parameters in the procs.  Now it looks like the MySQL provider is converting the MySQL longblob type to clr type of object.  This is throwing an error caused by this method in the SqlConnectionProvider class…
public static DBColumnType GetColumnType(DbType type, bool supressExceptionOnUnknown) {
switch(type) {
…
case DbType.Guid:
return DBColumnType.Guid;
case DbType.Object:
if(supressExceptionOnUnknown) {
throw new InvalidOperationException(type.ToString());
}
return DBColumnType.Unknown;
default:
throw new InvalidOperationException(type.ToString());
}
}

To recreate the error, add a proc that has a parameter with a blob type.