Weird behaviour of CI after a redirect() - codeigniter

Question

I have a strange bug during the password recovery process.
When a user loses his pwd, the app send an email with a token inside the recovery link ( http://localhost/reset-password/f38fd00aa975b28c70f54d948d20de40 for exemple ) This token is an unique key inside the user table.
In the routes.php, i have :
$route['reset-password/(:any)'] = "/user/reset_password_form/$1";// new password form
$route['reset-password'] = "/register/reset_password"; //simple email form
then, reset_password_form generates a form with the token as hidden input :
public function reset_password_form($hash = NULL) { //create form to change password, with user validation hash inside
$user_id = $this->user_model->get_id_by_confirmation_code(strip_tags($hash));
if (isset($user_id)) {
$this->data['validation_code'] = $hash;
$this->data['title'] = $this->lang->line('user_title_password_edit', FALSE);
$this->template->load('default', 'register/reset_password_form', $this->data);
}
else{
$this->session->set_flashdata('error', $this->lang->line('user_error_reset_password', FALSE));
redirect('reset-password');
}
the view:
<?php $attributes = array('class' => '');
echo form_open('user/edit_password', $attributes) ?>
<input type="hidden" id="validate" name="validate" value="<?=$validation_code?>">
<div class="form-group">
<input type="password" id="password" name="password" placeholder="Password" class="form-control" value="<?php echo set_value('password'); ?>">
</div>
<div class="form-group">
<input type="password" id="password_confirm" name="password_confirm" placeholder="Password confirmation" class="form-control">
</div>
<button type="submit" name="submit" class="btn btn-success">Change password</button>
</form>
Finally, the user/edit_password function changes the user password with a new one.
public function edit_password() { //get new password and change it
$this->form_validation->set_rules('password', 'Password', 'trim|required|min_length[6]');
$this->form_validation->set_rules('password_confirm', 'Confirm Password', 'trim|required|matches[password]');
$this->form_validation->set_rules('validate', 'Validate', 'trim|alpha_numeric|required');
if ($this->form_validation->run() === false) {
//STRANGE BUG
$URL = '/reset-password/'.$this->input->post('validate');
$this->session->set_flashdata('error', validation_errors());
redirect($URL);
}
else {
//change pssword
}
}
The bug happen when the form validation fail : i'm suposed to be redirected to the previous form ( /reset-password/hash) with a flashdata error message, but the error message dont display.
Much more weird : even if i'm on the right form ( but without error message) if i decides to click on another menu item (for exemple /home) , it immediately displays the /reset-password form ( /register/reset_password in the routes) with the error message i was supposed to get previously.
As if the full php instruction was kept in stamp and launched after whatever action.
PS : as edit_password() and reset_password_form() are in the same controller, i could have used $this->reset_password_form($hash) instead of redirect() but it has exactly the same effect !
ps2: here is the register/reset_password:
public function reset_password() {
//display forgotten password form page
$this->data['title'] = 'Forgotten password';
$this->template->load('default', 'register/reset_password', $this->data);
}

Answer 1

you recovery link http://localhost/reset-password/f38fd00aa975b28c70f54d948d20de40 is not finding controller. CI is looking for your token number as controller