# Package =TWiki::AccessControlException Exception used raise an access control violation. This exception has the following fields: - `web` - the web which was being accessed - `topic` - the topic being accessed (if any) - `user` - canonical username of the person doing the accessing. Use the methods of the TWiki::Users class to get more information about the user. - `mode` - the access mode e.g. CHANGE, VIEW etc - `reason` a text string giving the reason for the refusal. The exception may be thrown by plugins. If a plugin throws the exception, it will normally be caught and the browser redirected to a login screen (if the user is not logged in) or reported (if they are and just don't have access).
## [[ClassMethod]] **new** `($mode,$user,$web,$topic,$reason)` - `$mode` - mode of access (view, change etc) - `$user` - canonical user name of user doing the accessing - `$web` - web being accessed - `$topic` - topic being accessed - `$reason` - string reason for failure All the above fields are accessible from the object in a catch clause in the usual way e.g. `$e->{web}` and `$e->{reason}` ## [[ObjectMethod]] **stringify** `() -> $string` Generate a summary string. This is mainly for debugging.