HTTP:payload replace - problem with French characters

Ah, that makes more sense. The ACCESS::restrict_irule_events command is allowing you to see the access policy process in the HTTP event structure, and subsequently failing when you try to modify a response in the stream. Here's something, albeit crude, that should work. I've combined both iRules into one.

when CLIENT_ACCEPTED { 
    ACCESS::restrict_irule_events disable 
}
when HTTP_REQUEST {
    STREAM::disable
    if { [HTTP::uri] ends_with "/my.logout.php3?errorcode=19" } { 
        HTTP::redirect "/" 
    } elseif { [HTTP::uri] contains "/public" } { 
        HTTP::header remove "Accept-Encoding" 
        if { [HTTP::version] eq "1.1" } { 
            if { [HTTP::header is_keepalive] } { 
                HTTP::header replace "Connection" "Keep-Alive" 
            } 
            HTTP::version "1.0" 
        } 
    }
}
when ACCESS_ACL_ALLOWED {
    set procstream 1
} 
when HTTP_RESPONSE {
    if { [info exists procstream] } {
        if {[HTTP::header "Content-Type"] contains "text"} {
            STREAM::expression {@flag:"true@flag:"false@} 
            STREAM::enable 
        }
    }
}

It may require some tweaking, but the idea is to make sure the access policy evaluation is complete before attempting to rewrite the server's response. The ACCESS_ACL_ALLOWED event is only triggered on requests AFTER the policy is complete.