If you are using Salesforce Files system in your Contract Management org, you may encounter an error when you check-in your agreement in X-Author Contracts. This occurs if adequate user-based settings are not configured in X-Author Contracts. To solve this problem, enable Salesforce CRM Content User setting for your users in your Salesforce org. This setting is present on the User Details page.

For more details on File System settings, refer to Comply System Properties topic in Contract Management on Salesforce Administrator Guide.