Grid exception

I am getting an exception when I execute the following line:

The exception contains following repeated text:
at java.lang.StringBuilder.append(Unknown Source)
at java.lang.String.valueOf(Unknown Source)

Previously I encountered this error when the bean added to the container had attributes that could not be rendered as a string. I removed these attributes from the container as follows:

However in this case I have used the removeContainerProperty method to remove everything I can think of and still have the error…

All suggestions welcome.

Kind regards