Explanation of the error
This Salesforce error that Gearset is surfacing is usually encountered when deploying a Custom object that references a Visual Force page with the API name <xxx>.
Resolution
To resolve this issue try adding Lightning page metadata to your metadata filter.
Further examples of this Salesforce validation error can be found here:
Disclaimer: This error is returned by Salesforce directly, rather than Gearset. Even so, we offer guidance based on our combined experience with the Metadata API. Where possible, we try to help guide you to fix or avoid this error. In the case that this isn't possible, we may need to direct you to Salesforce support for further clarification.