Excel reader error

[AlessandroPozzetto]

Hello community. When I run the excel reader file (https://github.com/oemof/oemof-examples/tree/master/oemof_examples/oemof.solph/v0.4.x/excel_reader) I get the following warning:

WARNING: Reassigning the non-component attribute dual on block (model).Model
with a new Component with type <class 'pyomo.core.base.suffix.Suffix'>.
This is usually indicative of a modelling error. To avoid this warning,
explicitly delete the attribute:
del Model.dual

It appears when the "om.receive_duals()" function is called.
I'm running the original code without any modifications from my side.

Can anybody help me in understanding what might be the reason and what its consequences might be?

Thank you very much in advance!

[p-snft]

The issue should be fixed with oemof/oemof-solph#842, which is to be released with v0.5. To my understanding, there is no real failure.