Themes

I believe with that notification your theme is Essential?

You should test it on  separate 'development' server with your plugins and activities (but then you should do that with any upgrade and any theme or plugin addition anyway )

I do have Essential running on a 3.1 test environment - I have definitely not run comprehensive testing with it at all, just have it there and used it for a few things and it hasn't broken anything. BUT Gareth will probably NOT support it until he officially releases a version that he is happy to have tested and released as suitable for 3.1 and I don't think he has done that for Essential yet (not in the plugins database that i can see anyway)

It depends on which theme, and how it is made.

Generally the old themes like Afterburner, Brick, Boxxie etc still work as there is nothing much in them that would conflict.

All the themes that need updating will have been updated, although I did notice not many have updated yet.

If it is loaded and works then I would not worry too much, as the changes are mainly in Moodle Core and the ones in the Bootstrapbase and Clean only add a new feature.

So the only problems likely to break in a theme would be if there is a renderer in that theme that is used to change something in Moodle. If the renderer in Moodle is different than a previous version, then that would be enough to trigger a warning or error message.

This is the UPGRADE.TXT from Moodle 3.1 (moodle/theme/upgrade.txt)

This file describes API changes in /theme/* themes,
information provided here is intended especially for theme designers.

=== 3.1 ===

* A new search box for global search has been added to bootstrap and clean layout files, if
  your theme is overwriting columns1.php, columns2.php or columns3.php you will need to add a
  call to core_renderer::search_box to display it.
* Notification templates have been renamed to better suit types of alert
  rather than uses. The following changes have been made:
  * notification_problem.mustache => notification_error.mustache
  * notification_message          => notification_info
  * notification_redirect         => notification_warning
* Method core_course_renderer::course_section_cm_name() is split into two methods, custom themes that override
  this method must be modified or otherwise editing functionality may become broken. This method is now also used by social activities block and site menu block to display activities names.

First point:

The addition of a new Global Search box in Clean and Bootstrapbase layouts will not affect your theme, as it will not be added to your theme unless your theme is using Clean theme layouts.

Second point:

Notification have changed and these should not affect the theme. it's just that they work differently now.

Third point:

Method core_course_renderer::course_section_cm_name() 

This renderer type is the only thing that has the potential to break a theme,

So if your theme has this type of renderer then odds on it will break at some point.

As a matter of interest, which theme are you using?

Cheers

Mary