COMMIT TRANSACTION error when using ApplyUpdate()

This simple code is causing the follow error message when calling ApplyUpdates() method. This is in Delphi XE6 running the latest versions of DA. Any ideas why it might be doing this… it was working fine when I was pointed to a database hosted on Azure but have now moved the database to AWS RDS. Thanks!

tbl_Users.Open;
tbl_Users.AddRecord(['Email', 'UserName'], [aEmail, aUserName]);
tbl_Users.ApplyUpdates(False, False);

Hello

Unfortunately it is hard to say for sure without more information provided. Especially given that this worked on Azure earlier.
In general this error means that the currently running transaction is broken, but the code executing is not aware of it.
For example similar error can be raised due to a failing trigger. Could you try to connect to the database using some tool that allows direct code execution (like SQL Server Management Studio) and try to execute the same update query there? This will help to pinpoint the source of the error.

TIA

Hello

As per additional information provided:
Relativity Server running on a EC2 uses Mono.

Unfortunately it seems that due to a new Mono bug ( https://bugzilla.xamarin.com/show_bug.cgi?id=16892 ) it is not possible to set Db command parameter value to NULL . In result it is not possible to set table field values to NULL on update operations or to leave them set to NULL on insert operations.

We’ll start to work on proper workaround ASAP.