Async error: description
One of the following problems occurred:
- A hoisting error occurred within the body of an ASYNC method.
- The method returned an invalid return type.
- The version of the .NET Framework being used is lower than 4.5. ASYNC and AWAIT support is only available when compiled and run against Framework 4.5 or higher.
An ASYNC method cannot contain any of the following:
- A field that is a member of group or a named record
- A field that overlays or is overlayed by another field
- A parameter that is BYREF, OUT, INOUT, or a parameter group
- A return type other than void, Task, or Task<>