What specific issue can occur if the flow is referenced incorrectly in a flow URL?

When a flow is referenced incorrectly in a flow URL, it can lead to an invalid URL error. This occurs because the system relies on the proper structure and accuracy of the URL to identify and access the specific flow. An invalid reference means that the system cannot locate the flow attached to that URL, resulting in an error notification that typically indicates that the flow cannot be found or does not exist.

The other options, while they detail potential consequences of flows that execute improperly, do not specifically address the scenario of an incorrectly referenced URL. Hence, the primary effect of an erroneous URL is represented by the issue of invalidity, accurately reflecting the nature of the problem at hand.