C# 8 and .NET Core 3 Projects Using Azure - Second Edition

AllowSynchronousIO

In .NET Core 3.0, a breaking change was introduced, whereby the default of allowing synchronous calls was changed so that they were not allowed. At the time of writing, BotFrameworkAdaptor breaks that rule (perhaps because it's using Newtonsoft JSON serialization—in which case this may not be an issue by the time this book is published). You might get the following error when running the project:

System.InvalidOperationException: Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead.'

The following changes should be implemented only if you get the preceding error when running the project:

1. In BotController, change the AllowSynchronousIO flag:

[HttpPost]
public async Task PostAsync ...