Reproduce:

• Have two process definitions, A and B
• A has two versions 1 and 2, B has only one version 1
• goto process instance migration page, select souce: Av1, target Av2
• change target process definition to B

Expected:

• Since there is no version 2 for process definition B, either the version is automatically set to the latest version, or there is an error indicating that the current selection is invalid
• In case the version is not set to a valid version, the Proceed button should be disabled

Observed:

• No error message, diagram does not get updated
• Proceed button is enabled and performs like the old process definition is still in place