Error AGREEMENT_NOT_SIGNABLE when requesting a signing URL

Hello everyone,

I'm creating an agreement via Sign API like this:

1. upload a document

2. create an agreement

3. get the signing URL to redirect user to sign

It often works, but sometimes on step 3 I get a 404 with

{"code":"AGREEMENT_NOT_SIGNABLE","message":"The agreement is not currently waiting for anyone to sign it"}

And even in the case of error the user is still able to sign the agreement with the link he received via email.

I'd like to know if my flow is correct(it seems so, since it works mostly). What does the error mean — is it a race condition and I just have to retry? Or are there edge cases I'm missing?

Thank you