When Spanning attempts to back up an object type in your Salesforce environment, Spanning sends a request to Salesforce to retrieve data for that object type. Salesforce requires us to list all fields for the object type when making that request. Sometimes, if an object type has a large number of fields and / or fields with long names, the total length of the request will be too long, and Salesforce returns an error message: "Request Entity Too Large: Head".
This is a limitation of Salesforce's API, and Spanning is currently working on a long-term fix for this issue. In the meantime, we have developed a work-around:
Contact email@example.com with a list of fields in the object type in question that can be excluded from the backup. There should hopefully be fields in this object type that are extraneous, and unnecessary to be backed up.
The Spanning engineering team will then exclude the listed fields from your daily backup to lower the total number of characters below the imposed Salesforce limit.
If you have any questions, please reach out to firstname.lastname@example.org.