As reported by Victor Deniz in https://tracker.moodle.org/browse/MDL-61899?focusedCommentId=609945&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-609945

1. Delete the child user.
2. As the user with parent role, access Data requests.

   Error message:

   Invalid user

   More information about this error

   ×Debug info: SELECT id FROM {user} WHERE id = ? AND deleted = ?

   [array (

   0 => '78',

   1 => 0,

   )]

   Error code: invaliduser

   ×Stack trace: * line 1546 of /lib/dml/moodle_database.php: dml_missing_record_exception thrown

   line 1522 of /lib/dml/moodle_database.php: call to moodle_database->get_record_select()

   line 6105 of /lib/accesslib.php: call to moodle_database->get_record()

   line 78 of /admin/tool/dataprivacy/classes/output/my_data_requests_page.php: call to context_user::instance()

   line 51 of /admin/tool/dataprivacy/classes/output/renderer.php: call to tool_dataprivacy\output\my_data_requests_page->export_for_template()

   line 412 of /lib/outputrenderers.php: call to tool_dataprivacy\output\renderer->render_my_data_requests_page()

   line 61 of /admin/tool/dataprivacy/mydatarequests.php: call to plugin_renderer_base->render()