Concurrency::task.wait() throws invalid_operation exception: "Illegal to wait on a task in a Windows Runtime STA."

This exception occurs since ~14th November 2022 and seems to be Microsoft update related.

The exception does not occur, when building in Debug mode. Edit: it was true only for some Visual Studio versions. The latest release do throw the exception regardless of Debug or Release modes.

The code runs in a C application as managed-C .

Any known Microsoft issues in this direction? Edit: the exception seems to be correct but it never showed up until some updates.

CodePudding user response：

I've also only recently encountered this error without any known changes to the code.

my issue involves the Microsoft C Rest SDK. specifically a call like

try {
        response = client.request(request).get();
} catch (...) {
}

CodePudding user response：

The issue appears if single threaded COM initialization via CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); or CoInitialize(NULL); is done prior to calling Concurrency::task.wait().

The issue can be fixed by initializing COM with

CoInitializeEx(NULL, COINIT_MULTITHREADED);

or

Windows::Foundation::Initialize(RO_INIT_MULTITHREADED);

If you want to call Concurrency::task.wait() on a thread which is already initialized as COINIT_APARTMENTTHREADED and you cannot change it - start your concurrency task in a new thread via e.g. std::thread.