Full Error Message:
eSign server error. Recipient Sign View. Error occurred when updating document with EncodedId (e79e6d02-f6b0-43ba-8690-10850db7b4cb) open date in salesforce.
You may also get a similar error about updating another field.

Reason for error: 

The A5 Signature application that is outside of Salesforce is trying to make an update to the eSign Doc record in your Salesforce org. For some reason the app is unable to update the record. This could be because it cannot access the record specifically or cannot access your Salesforce org.

Things to Check to Resolve the Error:

  1. Search for the specific eSign Doc record referenced in the error to locate it by searching the EncodedId. In the sample above this would be “e79e6d02-f6b0-43ba-8690-10850db7b4cb”. The EncodedID is a field on the eSign Doc object and is an external unique id for the record. If you cannot find this record, it may have been deleted by a user. Maybe it was sent as a test or sent and then user decided to delete it. You may check the Recycle Bin in Salesforce and undelete it.
  2. Under eSign Configuration tab during the initial setup of A5 Signature, an admin user clicked the Grant Access button. If you check this page you can confirm that someone has still granted access and check which user has granted access. Consider that this is the user that is attempting to update the record. Does this user have permission to update this record and these fields on this object. You can verify if you login as that user and attempt to update the record. You may click Grant Access again using another User logged into to change which user is making the update.
  3. An admin may have updated security settings in Salesforce to not allow any updates via the API or external systems. 
  4. The Salesforce org may be locked out for some reason.
  5. Your org may have reached its API call limits for the last 24 hours. You can check your API usage by going to Setup > System Overview > API Usage.
  6. Salesforce could be down at the moment. You can check https://trust.salesforce.com for the current status.