ERR_TOO_MANY_REDIRECTS on Shopify
Why it happens on Shopify
A domain pointed at Shopify through a third-party proxy or a CNAME on the apex creates a loop between the proxy's redirect and Shopify's own canonical-domain redirect.
The fix on Shopify
Point the apex at Shopify's A record directly and www via CNAME, with no intermediate proxy. Then set the primary domain in Settings → Domains so only Shopify performs the canonical redirect.
Is ERR_TOO_MANY_REDIRECTS happening on your domain?
The uptime probe returns the full redirect chain, so you can see the exact two URLs bouncing off each other instead of inferring it from behaviour.
Free, no signup. Runs from outside your network, which is the only way to tell a server fault from a local one.
If that didn't fix it
Shopify has its own failure mode, but ERR_TOO_MANY_REDIRECTS has a wider set of causes that apply everywhere. The most common one overall is: the cdn forwards to the origin over http while the origin redirects all http to https — an infinite loop.
All causes and fixes for ERR_TOO_MANY_REDIRECTS