Salesforce Error When Uploading New Agreement

I keep receiving this error message when uploading a new agreement to use with the Adobe Sign app inside the Salesforce CRM.

Error message:  [Cannot read property 'length' of null]

I have also tried uploading a file via salesforce first and using the uploaded file as the agreement being sent out, but it also returns this error message: Uncaught Action failed: echosign_dev1:DocumentSelector$controller$onAddFiles [Cannot read property 'length' of null]

Here is a screenshot as well of the error message, any help would be greatly appreciated. Screenshot: 2018-08-27_1103