Eloy wrote in MDL-27551:

To reproduce: Install Moodle 2.1 with the CLI installer, you will get:

Moodle 2.1dev (Build: 20110602) command line installation program
-->System
PHP Notice: Undefined property: stdClass::$defaultuserroleid in /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php on line 6510
PHP Stack trace:
PHP 1.

() /Users/Shared/Jenkins/Home/moodle_integration_git/admin/cli/install.php:0
PHP 2. install_cli_database() /Users/Shared/Jenkins/Home/moodle_integration_git/admin/cli/install.php:648
PHP 3. install_core() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/installlib.php:555
PHP 4. admin_apply_default_settings() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/upgradelib.php:1376
PHP 5. admin_apply_default_settings() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:5855
PHP 6. admin_apply_default_settings() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:5855
PHP 7. admin_apply_default_settings() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:5855
PHP 8. admin_setting_enablemobileservice->write_setting() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:5869
PHP 9. admin_setting_enablemobileservice->set_xmlrpc_cap() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:6634
PHP 10. admin_setting_enablemobileservice->is_xmlrpc_cap_allowed() /Users/Shared/Jenkins/Home/moodle_integration_git/lib/adminlib.php:6528
It seems that you are trying to use $defaultuserroleid before it has been defined, so it fails and I guess it causes the behavior of is_xmlrpc_cap_allowed() to fail too.

Surely that code needs to check if we are in early installation stages - during_initial_install() - and act in consequence. Or be executed later - lib/db/install.php - or whatever but current incarnation seems wrong.