Attempting to remove shared users and roles from a parent portal, I get this error:
A critical error has occurred.
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

What is causing?

Also, why does this module do so many postbacks?

What module and dnn version are you running ?

DNN5.6.3 and DNN Masters MPUS X-treme 2.1.18, says the upgrade is available 2.01.25 but it's not on snowcovered.

You should be running 2.1.22 - it's on snow under product downloads

Thanks I will try it, I thought it was for DNN6!

3.1.1 is for dnn 6.x

Updated to 2.1.22 but still getting same error when I try to remove a group from SA.

I can't reproduce this issue. I can add and delete groups without errors.

I deleted the SA and now its working, my bad.
thanks.

Question;
I want to share only some users from a role in the main portal to the parent portal, do I need to share the role and then can I select users to share?

You don't have to share the role if it's only users that you need to share.
Unless of course you want the users to have the same role on shared portal and the role doesn't exist there.

The module postbacks about three times when I make any change, the module bounces over the page at least that many times. Not sure what is causing this. but my big problem now is that the MPUS is grabbing the wrong http alias for the main portal, when users logout they get taken to another http alias.
What should http alias settting be? NONE - CANONICAL - REDIRECT???

This is solved in 3.1.1 by adding an option to select aliases to be used for SSO.
In 2.x you can use core dnn redirect to correct alias.

when I add SA and add both portals I have errors authorizing users in main portal. Have you seen that before?

No, it works correctly for me.
I can add users and they will be authorized.

Deleting SA requires multiple tries, and usually I get the postback error I showed above, then finally after five or six times, it deletes.
The module is not working correctly in my environment.

Continue to get this postback error when I try to modify settings;
A critical error has occurred.
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

Version 2.1.23 released. It should prevent the issues that you observe.

Where do I get the latest version? The latest on Snow is 2.1.23 but my instance shows the latest version is 2.1.25.