Reproducer:

• In webui, go to dashboard and click "Setup Cluster"
• In displayed wizard, type cluster name and necessary nodes
• Continue to "Advanced options" > "Transport Options"
• Click "Add link" and fill necessary fields
• Continue to review and click "Setup Cluster"
• You get an error (depending on backend version)

Background:

Webui sends "linknumber" as integer. However, backend pcsd tightened the type checking of the request - the "linknumber" must be string.