gpg: keyserver receive failed: General error

Toying with anbox, I was re-compiling my kernel to add the needed modules -ashmem and binder- now included on the mainstream linux kernel, I faced an annoying problem with GPG keys from Jan Alexander Steffens (3B94A80E50A477C7).

The usual step is add the key with the recv-key command, but endend with the error

$ gpg --recv-key 3B94A80E50A477C7
gpg: keyserver receive failed: General error

The solution is to ask another server for that key, like follows:

$ gpg --keyserver pool.sks-keyservers.net --recv-key 3B94A80E50A477C7
gpg: key 19802F8B0D70FC30: 6 duplicate signatures removed
gpg: key 19802F8B0D70FC30: 6 signatures reordered
gpg: key 19802F8B0D70FC30: public key "Jan Alexander Steffens (heftig) <jan.steffens@gmail.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1


I let you here some useful key server if you face this problem with a missing key:

pool.sks-keyservers.net
pgp.mit.edu
keys.openpgp.org
keyserver.pgp.com
keyserver.ubuntu.com