F# : Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead

Question

While executing the POST or PUSH requests in Postman for the following repository (https://github.com/websharper-samples/PeopleAPI),

I am getting this error : System.InvalidOperationException: Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead. Error Screenshot

How do I set AllowSynchronousIO to true in f# to execute POST or PUSH requests for an API?

Answer 1

Extremely late to the party. I had this problem with Giraffe F#. Fixed it by changing

WebHostBuilder()
    .UseKestrel()
    .UseContentRoot(contentRoot)
    .UseIISIntegration()
    .UseWebRoot(webRoot)
    .ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureAppConfiguration)
    .Configure(Action<IApplicationBuilder> configureApp)
    .ConfigureServices(configureServices)
    .ConfigureLogging(configureLogging)
    .Build()
    .Run()

to

WebHostBuilder()
    .UseKestrel(Action<KestrelServerOptions> configKestrel)
    .UseContentRoot(contentRoot)
    .UseIISIntegration()
    .UseWebRoot(webRoot)
    .ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureAppConfiguration)
    .Configure(Action<IApplicationBuilder> configureApp)
    .ConfigureServices(configureServices)
    .ConfigureLogging(configureLogging)
    .Build()
    .Run()

and the configKestrel function looks like:

let configKestrel (opts : KestrelServerOptions) =
    opts.AllowSynchronousIO <- true