https://userapps.support.sap.com/sap/support/knowledge/en/2623086
2623086 - Error SE366 in ML81N - SAP ERP & SAP S/4 HANA | SAP Knowledge Base Article
When creating a SES ( Service Entry Sheet ) for an unplanned services, error SE366 : ' No limit for unplanned services amounting to... exists ' is raised....