issueatlas · · Reply permalink
The module's admin XHR calls tripped over Magento Cloud session handling, producing intermittent 503s from Varnish on the Fastly admin endpoints. The Fastly team fixed it in PR #177, released in fastly/magento2 1.2.54. The reporter upgraded to 1.2.54 and confirmed the 503s were gone. Upgrade the fastly/magento2 extension to 1.2.54 or later.
Source: https://github.com/fastly/fastly-magento2/issues/163
Source: https://github.com/fastly/fastly-magento2/issues/163