Hi, Marc!
I had one third-party application and three plugins active: having just disabled them all, I tried again, receiving the same error:
UPDATE `downloads_categories` `downloads_categories` SET `cname_furl`='trustees-2',`callow_anonymous`=false,`cparent`=0,`csortorder`='updated',`cdisclaimer_location`='download',`clog`=NULL,`ctypes`=NULL,`cmaxfile`=NULL,`cmultiple_files`=true,`cversion_numbers`='0',`cversioning`=0,`crequire_changelog`=NULL,`cmaxss`=0,`cmaxdims`='0x0',`ctags_disabled`=true,`ctags_noprefixes`=false,`ctags_predefined`=NULL,`cbitoptions`=133 WHERE cid=27
IPS\Db\Exception: Column 'crequire_changelog' cannot be null (1048)
#0 /home/xxx/public_html/system/Db/Db.php(1156): IPS\_Db->preparedQuery('/*esperant_main...', Array)
#1 /home/xxx/public_html/system/Patterns/ActiveRecord.php(520): IPS\_Db->update('`downloads_cate...', '`cname_furl`=?,...', 'WHERE cid=?')
#2 /home/xxx/public_html/system/Node/Model.php(2494): IPS\Patterns\_ActiveRecord->save()
#3 /home/xxx/public_html/system/Node/Model.php(3316): IPS\Node\_Model->save()
#4 /home/xxx/public_html/system/Node/Controller.php(419): IPS\Node\_Model->saveForm(Array)
#5 /home/xxx/public_html/applications/downloads/modules/admin/downloads/categories.php(79): IPS\Node\_Controller->form()
#6 /home/xxx/public_html/system/Dispatcher/Controller.php(90): IPS\downloads\modules\admin\downloads\_categories->form()
#7 /home/xxx/public_html/system/Node/Controller.php(69): IPS\Dispatcher\_Controller->execute()
#8 /home/xxx/public_html/applications/downloads/modules/admin/downloads/categories.php(44): IPS\Node\_Controller->execute()
#9 /home/xxx/public_html/system/Dispatcher/Dispatcher.php(153): IPS\downloads\modules\admin\downloads\_categories->execute()
#10 /home/xxx/public_html/admin/index.php(13): IPS\_Dispatcher->run()
#11 {main}
Notwithstanding the error, the categories were actually created: