Warning: Parameter 1 to mobile_codes_settings_form() expected to be a reference

I'm getting the same error in 7.x-2.0

change line 9 of mobile_codes.admin.inc to

function mobile_codes_settings_form($form) {

that will only get you the first setting the rest of the form is still missing.

an update to jucallme's reply

Edit "sites/all/modules/mobile_codes/includes/mobile_codes.admin.inc"
Just remove the "&" inside function mobile_codes_settings_form(&$form_state) { on Line 9

As of this date there is only one option there > "URL settings"

#3 worked for me

That function doesn't even need NOR GET the form_state.
And there was another of these call-by-reference issues found when enabling the module, patch attached, please review. :)

patch in #5 worked for me

Patch in #5 also worked for me.

Hope this module gets updated.
I use this module for my website so I can attach QR-Codes instead of regular attachments.

looks like this was already committed to dev

hummm, I couldn't see it in the current dev release.

Drupal 7 doesn't support passing by reference anymore as it was depreciated in php 5.3 - Perhaps preaching to the converted there but that's the history to it anyway. :-)

The new dev from 6/25 does not have the patch in #5 in it.

Fixed and committed.