We recently ran into an issue with some of our auto-generated URL title on channel entries. It seems that EE will happily allow characters like periods in URL titles. For example if I had a tile like U.S. Tops in EE Installs then the generated URL title is u.s.-tops-in-ee-installs. The periods can become an issue in some cases. Specifically they seem to throw off the EE Session Tracker Array, causing it to be NULL which is what caused our problem. So my questions are:

  1. Why does EE even allow these kinds of characters in URL titles?
  2. Is there a setting or way to define a list of disallowed characters to be stripped from URL titles?
  • Why does EE even allow these kinds of characters in URL titles? They are valid in URLs, but more specifically, some sites require dots and extensions to mimic files, product IDs, or other existing names/assets/resources, etc. It does sound like you have discovered a bug though. Do you mind putting in a report so our engineers can take a look? Commented Aug 8, 2014 at 20:46
  • I'd be happy to file a report. Thanks Derek. Commented Aug 13, 2014 at 1:05

1 Answer 1


Pop open your config file: /system/expressionengine/config/config.php

Look for a config option for 'permitted_uri_characters' - if you don't have it, you can add the line:

$config['permitted_uri_chars'] = "a-z 0-9~%.:_\-";

This is what I use (and I think it's the default). But you should be able to just remove the period.

If you use Structure (or similar), there's probably additional steps you'll want to take. So make sure you do proper testing, and so on.

  • Perfect. This is exactly what I was looking for. Thanks. Commented Aug 13, 2014 at 0:55
  • This might not be the answer. I went to the config.php and I see this in the comments: The following items are for use with ExpressionEngine. The rest of the config items are for use with CodeIgniter, some of which are not observed by ExpressionEngine, e.g. 'permitted_uri_chars' Commented Aug 13, 2014 at 1:00
  • Ok, so there for sure is some conflicting information here. This github does show that permitted_uri_chars IS a hidden variable for EE, so what's reality? Commented Aug 13, 2014 at 1:07
  • I think this is going to be a case of "try and and see what happens." You have a dev site you can test on? Try updating that item in config.php. Clear your caches for good measure. Then try creating a new post. As you fill in a title, the page url should drop the unallowed characters. And if you try to save the page w/ unallows chars in the URL, it should give you an error...
    – SamC
    Commented Aug 14, 2014 at 15:53
  • Good advice @SamC and yes I do have a dev environment to test in. Commented Aug 15, 2014 at 17:27

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