Initial setup, challenge file does not match

I am using this rails gem, trying to integrate with heroku

I am getting this error

E, [2016-05-03T21:59:13.695678 #3] ERROR – : Challenge verification failed! Error: urn:acme:error:unauthorized: The key authorization file from the server did not match this challenge [fCIE5wiFCtlx9UHEgKTswzC4PRceS0wb6zPhs0hovYs.EBQ1RdJR0HmZ97rzoMbUwwxwhjHvgIZh2DCztaKf3m8] != [J8nt7FyzIWmQL9ejwpwZJGvLo-86c2JJYwNPFqFYLxs.EBQ1RdJR0HmZ97rzoMbUwwxwhjHvgIZh2DCztaKf3m8

I guess I must have tried something locally and the identity of the server is not recognized… that’s my guess

how do I start over? how do I tell lets encrypt to forget about my previous trials ?

or is this caused by something else ?

i locally created the keyfile like this

openssl genrsa 4096 > key/keyfile.pem

following these instructions github link above /wiki/Installation-guide

thank you