1. Create problems and suppress them;
2. create a Problems by severity widget:
3. enable "Show suppressed problems" and save widget;
4. observe runtime errors:

Undefined index: suppress_until [zabbix.php:22 -> require_once() -> ZBase->run() -> ZBase->processRequest() -> ZBase->processResponseFinal() -> CView->getOutput() -> include() -> makeSeverityTotals() -> getSeverityTableCell() -> makeProblemsPopup() -> isEventRecentlySuppressed() -> CConfigFile->{closure}() in include\events.inc.php:470]
Undefined index: suppress_until [zabbix.php:22 -> require_once() -> ZBase->run() -> ZBase->processRequest() -> ZBase->processResponseFinal() -> CView->getOutput() -> include() -> makeSeverityTotals() -> getSeverityTableCell() -> makeProblemsPopup() -> CConfigFile->{closure}() in include\blocks.inc.php:676]