At approximately 07:38 UTC on 9th September 2020, we experienced delays with contact imports in our US region. We restored services at 08:37 UTC on 9th September 2020.
Our contact import system loads a large suppression list file on startup. This file is stored in a cloud storage service, and in this instance the cloud storage service responded unexpectedly slowly. Once it had successfully loaded, we were able to process customer contact imports again.
The timeline for resolving this issue was:
The mechanism we use for loading the suppression file has been in production for many months without causing a prior issue. However, it will be altered to handle slow loading, and make it easier for multiple services to access cloud storage concurrently without incident.