When connecting Salesforce to SigParser if you get this error:
OAUTH_APPROVAL_ERROR_GENERIC: An unexpected error has occured during authentication. Please try again
Suggest looking at the URL of the page to see if there is a better description of the cause.
For example:
https://example.com?error=OAUTH_APP_BLOCKED&error_description=this+app+is+blocked+by+admin
You need to do one or more of the following:
Grant the user the permission Approve Uninstalled Connected Apps
As an Admin in Salesforce go to Setup -> Connected Apps OAuth Usage -> Find the SigParser app -> click Install
Sandboxes - Run the "Match Production Licenses to Sandbox without a Refresh " tool in the effected sandbox environment, more details on this tool can be found here
You can find a full help article about this issue on the Salesforce support portal.