Actually, I do mean there's no way to clear the pageMessages.  A browser redirect doesn't clear down the existing variables, it discards the controller and all associated information and a fresh one is created when the request is received.  This does seem like an oversight on the SFDC side but I guess its one we're stuck with.

You are correct on the constructor.  However, if the controller looks for the parameters anywhere else then the new values will be picked up and acted upon.

I think anywhere else would have to be a user prompted action or embedded actionFunction since I don't think action functions on apex:pages are called on cached pages either...

A getter that interrogates the URL would also be prone to this, I think.

Guys, try the code below:

Note value of  strDebug. ApexMessages is cleared when you return the PageReference of itself. Not all values are destroyed. Apparently, strDebug retains its ViewState value (otherwise it will get its constructor value) and page messages are cleared.

Hope this solves the posters question 

Controller:

public with sharing class ErrorPOC 
{
	public String strDebug {get;set;}
	public Account account {get;set;}
	public ErrorPOC()
	{
		account = new Account();	
		strDebug = 'Generated During Constructor Execution';
	}
	public PageReference generateError()
	{
		strDebug = 'Generated During Action Function';
		PageReference pref = Page.ErrorPOC;
		try
		{
			Database.insert(account);
		}
		catch(DMLException ex)
		{
			ApexPages.addMessages(ex);
		}
		return pref;
	}	
	public PageReference clearError()
	{
		PageReference pref = Page.ErrorPOC;
		return pref;
	}
}

VF Page:

<apex:page controller="ErrorPOC">
<apex:form >
	<apex:pageMessages />
	<apex:outputText value="{!strDebug}" />
	<br />
	<apex:commandButton value="Generate Error" action="{!generateError}" />
	<apex:commandButton value="Reset Error" action="{!clearError}" />
</apex:form>
</apex:page>

Regards,

AcMEGX

I've observed this before and actually I think that any function like this:

public PageReference refresh() {
  return null;
}

Will actually also produce the same results, whether or not it is documented.

See my latter post with code on the thread. Basically its calling a PageReference to itself, this way we clear APEX messages while RETAINING other Viewstate values. 

PageReference pref = Page.YOURVFPAGE; 

 pref.setRedirect(false); 

pref.getUrl();   -> this will reset ApexPages.Messages

is as good as:

    PageReference pageRef = ApexPages.currentPage();
    pageRef.setRedirect(false); 
    return pageRef;

which you have probably already deduced.

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d3developer wrote:

  AcMEGX,

  Don't understand your attempted solution. How would that fix anything? It doesn't even relate to the currentPage, which to my knowledge is the only PageReference which can hold page messages.

---

OOpss... sorry...setRedirect(true) will clear the viewstate. The reverse though is true

Should be 

PageRef.setRedirect(false);