Cant build docker ubuntu image on circleci

Reading package lists…
W: GPG error: trusty-pgdg InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 7FCC7D46ACCC4CF8
W: The repository ‘ trusty-pgdg InRelease’ is not signed.
E: Failed to fetch mirror:// Hash Sum mismatch
E: Failed to fetch mirror://
E: Some index files failed to download. They have been ignored, or old ones used instead.

How to fix it???