I don't know if this is the right forum for this issue, since it's theme-related (even though it's a coding issue). I am sorry if it's not.
Before 3.7, I could create a simple theme based on Boost with just the following lines in config.php:
defined('MOODLE_INTERNAL') || die();
$THEME->name = 'boost_custom';
$THEME->sheets = ['boost_custom'];
$THEME->editor_sheets = ;
$THEME->parents = ['boost'];
$THEME->enable_dock = false;
$THEME->yuicssmodules = array();
$THEME->rendererfactory = 'theme_overridden_renderer_factory';
$THEME->requiredblocks = '';
$THEME->addblockposition = BLOCK_ADDBLOCK_POSITION_FLATNAV;
However, after upgading one of my development installations to 3.7 I am getting the following error:
Coding error detected, it must be fixed by a programmer: page layout file [dirroot]/theme/boost/layout/ does not contain the main content placeholder, please include "<?php echo $OUTPUT->main_content() ?>" in theme layout file.
When printing the $layoutfile variable defined in lib/outputrenderers.php I am getting:
Instead of, for example:
To solve it, I just need to copy the $THEME->layouts property from boost into my child theme. But is it really necessary? Has anything changed in the way that child themes work?