Variable is not of known iterable type

Hi,
When i run my bot in control tower i have the next error:
Step name ‘AGR-Comunicar’ has failed. Reason: ‘[urn:uuid:6FD7E42C8B7C694B5F15814495082746416] robotics-flow executePlugin exception: [nodeId=http://127.0.0.1:15411] java.lang.IllegalStateException: Variable ‘info_reclamo_lista’ is not of known iterable type (class com.workfusion.studio.rpa.recorder.api.types.RString instead)’

What it mean? The bots work good in desktop.