eSignature does not launch at all
If you tried to use eSignatures and HelloSign dialog does not launch at all, you might be out of credits.
Each new organisation gets 10 free eSignatures and after that organisation owner is required to pre-pay a package of eSignatures (typically 100 documents each time).
Go to Settings > Plan and billing details and purchase a package of pre-paid eSignatures.
Clients get a message '404' when they try to sign documents
This typically happens when you use the same email address for multiple applicants. eSignatures are a legal document and they require each signatory to have a unique email address. This address and the IP address of the device used to sign are a potential proof in court that document was signed by the intended person.
The 404 error page can also happen if the applicant is attempting to sign the same document which was successfully previously signed.