No assembly found containing an OwinStartupAttribute, owinstartupattribute

No assembly found containing an OwinStartupAttribute, owinstartupattribute

After adding the SignalR class library using NuGet in ASP. net mvc, when the program runs again, an exception occurs:

Server Error in '/'application. The following errors occurred while attempting to load the app.
-No assembly found containing an OwinStartupAttribute.
-No assembly found containing a Startup or [AssemblyName]. Startup class.
To disable OWIN startup discovery, add the specified etting owin: AutomaticAppStartup with a value of "false" in your web. config.
To specify the OWIN startup Assembly, Class, or Method, add the specified etting owin: AppStartup with the fully qualified startup class or configuration method name in your web. config.

Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details:System. EntryPointNotFoundException: The following errors occurred while attempting to load the app.
-No assembly found containing an OwinStartupAttribute.
-No assembly found containing a Startup or [AssemblyName]. Startup class.
To disable OWIN startup discovery, add the specified etting owin: AutomaticAppStartup with a value of "false" in your web. config.
To specify the OWIN startup Assembly, Class, or Method, add the specified etting owin: AppStartup with the fully qualified startup class or configuration method name in your web. config.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Find some information on the Internet and solve the problem. Try the following steps and forget it here: