This incident has been resolved.

Buys and sells were temporarily unavailable earlier today due to site stability. High volume caused slow performance in one of our databases, and GDAX temporarily entered post-only mode due to availability issues with its REST API (in accordance with its Trading Rules). We have made several improvements and continue to monitor for stability.

Buys and sells are currently operational. They were temporarily unavailable during these periods:
8:04 - 9:06 a.m. PST
9:35 - 10:26 a.m. PST

Due to today's high traffic, buys and sells may be intermittently offline. We're working on restoring full availability as soon as possible.