Disabled JSF commandButton not firing after re-enabling by JavaScript

You need to enable the button by JSF, not by JavaScript/HTML DOM. During processing of the form submit, JSF will verify in the server side view state as well if the button is enabled or not, as part of safeguard against tampered requests.

E.g.

<p:commandButton id="btnAJAX" value="AJAX" action="#{bean.someAction}" disabled="#{!bean.enabled}" />
<p:commandButton id="btnEnabler" value="Enable" action="#{bean.enableButton}" process="@this" update="btnAJAX" />

with

private boolean enabled;

public void enableButton() {
    enabled = true;
}

public boolean isEnabled() {
    return enabled;
}

Make sure that the bean is at least @ViewScoped and not @RequestScoped, otherwise the action of button will still fail because the bean is recreated during the form submit request and thus the enabled property will become the default value, which is false.

See also:

• commandButton/commandLink/ajax action/listener method not invoked or input value not set/updated
• Does JSF prevent calls to unrendered managed bean actions by tampered requests
• How can I create toggle buttons in JSF?
• Force JSF to process, validate and update readonly/disabled input components anyway