Consider the use of TextWriter async methods for the HTML Helpers, for example the WriteInitializationScript methods. In certain scenarios the use of the synchronous methods causes an exception: System.InvalidOperationException: Synchronous operations are disallowed. Call WriteAsync or set AllowSynchronousIO to true instead.
This can be resolved by explicitly enabling synchronous operations
services.Configure<IISServerOptions>(options =>
{
options.AllowSynchronousIO = true;
});though synchronous operations have been disabled by default at framework level as of .NET 3.0.
Hello Julien,
Thank you for the details provided.
The item in the Feedback Portal is updated. The required behavior is planned for implementation in Q2 2026:
Best Regards,
Anton Mironov
Progress Telerik
Love the Telerik and Kendo UI products and believe more people should try them? Invite a fellow developer to become a Progress customer and each of you can get a $50 Amazon gift voucher.
