When attempting to add a block e.g. html block to a course category page, the following error is obtained:

Error writing to database

Debug info: Data too long for column 'pagetypepattern' at row 1
INSERT INTO mdl_block_instances (blockname,parentcontextid,showinsubcontexts,pagetypepattern,subpagepattern,defaultregion,defaultweight,configdata) VALUES(?,?,?,?,?,?,?,?)
[array (
0 => 'comments',
1 => '117',
2 => 0,
3 => 'admin-course-category',
4 => NULL,
5 => 'side-pre',
6 => 4,
7 => '',
)]
Stack trace:

• line 381 of /lib/dml/moodle_database.php: dml_write_exception thrown
• line 716 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
• line 759 of /lib/dml/mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
• line 594 of /lib/blocklib.php: call to mysqli_native_moodle_database->insert_record()
• line 628 of /lib/blocklib.php: call to block_manager->add_block()
• line 1017 of /lib/blocklib.php: call to block_manager->add_block_at_end_of_default_region()
• line 992 of /lib/blocklib.php: call to block_manager->process_url_add()
• line 1070 of /lib/pagelib.php: call to block_manager->process_url_actions()
• line 671 of /lib/pagelib.php: call to moodle_page->starting_output()
• line 565 of /lib/outputrenderers.php: call to moodle_page->set_state()
• line 165 of /course/category.php: call to core_renderer->header()