Salesforce Integration Error: Received exception event aura:systemError

When I click Send for Signature in Salesforce and enter all fields when I click next I get the following error message:
Received exception event aura:systemError

How I received the error was:

1. Go to Account or Opportunity in Salesforce
2. Click Send for Signature
3. Fill out all information
4. Attach document
5. Click Next - this is where the error occurs