CORS Error in Fetch
Angular client making requests for .well-known IS4 config resource was failing with CORS error (resource did not have allow-origin header).
As the error suggested, I hadn’t set up the right port on the CORS middleware in the IS4 host.
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services.AddCors(options => { // this defines a CORS policy called "default" options.AddPolicy("defaultPolicy", policy => { policy.WithOrigins(new[] { "http://localhost:5003", "https://localhost:44311" }) .AllowAnyHeader() .AllowAnyMethod(); }); }); |
And then implement that policy in the Startup.Configure method:
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app.UseCors("defaultPolicy"); |
It’s so easy to miss this when I’m changing projects around all the time.
I did find that my Chrome extensions were littering my console, too, which gave me false-negatives for CORS errors. So, to be sure, it’s worth opening an ‘incognito’ window for testing.