foreach (var user in userIdentifiers) { 
var response = await client.sendMsgAsync(
                              accesscode: paswoord,
                              userIdentifier: user,
                              title: "Lovapaanvraag",
                              body: "Zie .pdf bijlage voor uitgebreide informatie",
                              senderIdentifier: senderIdentifier,
                              attachments: jsonString,
                              coaccount: 0,
                              copyToLVS: false);

  int resultaat = Convert.ToInt32(response);
  if (resultaat != 0) geslaagd = false;      }

We are working in Blazor wasm.
After filling in a form, an entity gets created and added into the db. After that a .pdf gets created from the form and gets submitted to an external messaging-platform.
This messagingservice calls the above client.SendMsgAsync().
client.SendMsgAsync() is defined on an api we don’t control. It’s a given in this context.
When successful it returns an object-type which contains a 0.

When placing the messagingservice in a different project, I was able to unit-test it. It works.

When running directly in Blazor wasm I get the following error:

System.PlatformNotSupportedException: Cannot wait on monitors on this
runtime.

There definetely is information about this issue out there. If I understand it well, it’s a thread (blocking) issue.

In the end I have to be able to I suggest you extract the async work out of the sync code path and cache the results for use within the sync path.. Someone else put it as, I somehow need to get rid of the await.

Task.WhenAll() basically only displaces the issue (and provokes loss of information). So I’m quite at a loss how to solve this problem, that shouldn’t be so difficult.

Any suggestions, or new leads, would be greatly appreciated.