Api call from vercel to a proxied app fails

Hi everyone,

i really hope you can help me out. The issue is very weird. about 2 weeks ago the builds on my website started failing for no reason. The api call to a cloudflare proxied subdomain started failing with:

status: 503,
21:22:33.442  	    statusText: 'Service Temporarily Unavailable',

if i remove the proxy on that subdomain the api call succeeds and the build too.
i have checked with vercel support and they said it isnt from their end and sugegsted to look for an answer here.

any suggestions?

1 Like

You most likely ran into a challenge. Check your firewall events and depending on why it was challenged, make the necessary adjustments. If they use a fixed IP address, you can also whitelist it under IP access rules (not firewall rules).

i found the events.
Bot fight mode! but this isnt a bot.
and vercel uses dynamic ips so i cannot whitelist

is there anything else i could try?

Are these addresses from the same block? If so you could whitelist the whole block.

Alternatively you could also use an unproxied record.

they arent from the same block. i allowed the whole AS16509 AMAZON-02 but i am not sure this is smart

Yes, whitelisting the entire AS might not be ideal. In that case you could only disable it at https://dash.cloudflare.com/?to=/:account/:zone/firewall/bots.

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