pixel.wp.com 400, 499 status, failed to load resource

Hello all,

I’m seeing 400 and 499 errors on client sites from pixel.wp.com. Any idea how to troubleshoot this? Jetpack 5.3, WP 4.8.2.

JQMIGRATE: Migrate is installed, version 1.4.1
pixel.wp.com/g.gif?v=wpcom-no-pv&x_notes-menu-impressions=zero-jetpack&baba=0.5031548654655578 Failed to load resource: the server responded with a status of 499 ()
w.js Failed to load resource: the server responded with a status of 499 ()
mrp.js?adcca7562b9ef97d9dfa34de0eca2eb3:1915 [Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user’s experience. For more help, check https://xhr.spec.whatwg.org/.
request @ mrp.js?adcca7562b9ef97d9dfa34de0eca2eb3:1915
syndication Failed to load resource: the server responded with a status of 400 ()
pixel.wp.com/boom.gif?v=0.9&u=https://public-api.wordpress.com/pinghub&json={%22beacons%22:[%22pinghub.restproxy.ws_supported.chrome:1|c%22]} Failed to load resource: the server responded with a status of 499 ()
pixel.wp.com/boom.gif?v=0.9&u=https://public-api.wordpress.com/pinghub&json={%22beacons%22:[%22pinghub.restproxy.cookie.chrome:1|c%22]} Failed to load resource: the server responded with a status of 499 ()
pixel.wp.com/g.gif?v=wpcom-no-pv&x_notes-empty-message=all_shown&baba=0.35119312628886523 Failed to load resource: the server responded with a status of 499 ()
pixel.wp.com/g.gif?v=wpcom-no-pv&x_notes-empty-message=all_shown&baba=0.35215123542372595 Failed to load resource: the server responded with a status of 499 ()
pixel.wp.com/boom.gif?v=0.9&u=https://public-api.wordpress.com/pinghub&json={%22beacons%22:[%22pinghub.conn_open_dc.dca.chrome:291|ms%22]} Failed to load resource: the server responded with a status of 499 ()

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