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Let's say you upload a schema with two controls and build a form/step of your floe flow from that schema. Then you modify your schema and delete one of the controls from the xsd. You update the original schema with the modified one. When you go to the Form/Flow Home page, the form/flow may be flagged with an error. When schema update is done, any controls that were in schema that are no longer valid to that schema are "detached" and fall into the default from scratch schema. marks them in error to give the designer a visual cue that some investigation is necessary. The error message will clear if the form/flow is edited then saved even if the designer does not change anything.
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