.net core 5 app blocking due to CORS policy - asp.net-core-webapi

Question

I have created an api using .net core 5.0 but no matter what I do it seems to block my request to it giving the error
has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
my code in my startup.cs is
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
services.AddCors(options =>
{
options.AddPolicy("AllowAnyCorsPolicy", policy => policy.AllowAnyHeader().AllowAnyMethod().AllowAnyOrigin());
});
services.AddTransient<IChatLog, LogsData>(provider => new LogsData());
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseCors();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
});
}
From what I have read that should allow any requests from anywhere, but for some reason it is still blocking.
Has anyone any idea what is wrong?

Answer 1

Because app.UseCors() did not specify a policy name. You can add the name AllowAnyCorsPolicy.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
//...
app.UseCors("AllowAnyCorsPolicy");
//...
}

Answer 2

Use this syntax:
services.AddCors(o => o.AddPolicy("AllowAnyCorsPolicy", builder =>
{
builder.AllowAnyOrigin()
.AllowAnyMethod()
.AllowAnyHeader();
}));
and this too:
app.UseCors("AllowAnyCorsPolicy");