If you’re encountering a “TypeError: Failed to fetch” despite getting a valid response, it usually points to a CORS issue, network error, or credentials misconfiguration not a fetch syntax problem.
One likely cause is including credentials: “include” in your request, which requires the server to send proper CORS headers (like Access-Control-Allow-Credentials: true).
If those are missing or misconfigured, the browser blocks the response and throws a typeerror failed to fetch.
Ah, I ran into this last month! My API was responding just fine, but I still got the dreaded TypeError: Failed to fetch.
It turned out my server wasn’t returning Access-Control-Allow-Credentials: true while I was using credentials: “include” in the fetch request.
Once I added that header on the server side, the error disappeared instantly.
So yeah, it’s not always a bad fetch call, it’s often CORS mischief.
I faced this too, and the confusing part was the API did return data, but the browser refused to show it. In my case, it was due to a redirect, the server sent a 302 but didn’t carry over the CORS headers, and the browser blocked it.
If you’re using cookies or sessions, double-check that both the server and client are configured to handle credentials securely under CORS rules.
Yep, been there! One time I switched my local backend to HTTPS but forgot to update the fetch URL so the mixed content (HTTPS to HTTP) made the browser silently block the request and throw TypeError: Failed to fetch.
No obvious error in the network tab either! I’d recommend opening DevTools, checking the console and network tabs carefully those usually reveal if it’s CORS, network policy, or something odd like a preflight request failing.