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In terms of your error, the issue is that you are trying to display more than 1000 items on your board at a time and that isn't supported, for obvious reasons. This is a notice saying you exceeded the limit. You can ignore it but of course you won't see everything. The correct solution is to adjust your process such that you don't have a board trying to show that many items at once. This generally involves ensuring you are breaking up your work by areas and iterations and then having your board show only the iterations you care about. You can google for how to resolve this as it is a common question.