Try to fix the invalid trigger by going into each workspace Administration > Manage Service > Websheet Database Objects (on the right side region "Manage Meta Data). Click Validate Websheet Database Objects. The button "Correct Invalid Object" will display if any of APEX$ objects are invalid. Click the button to re-create the object. If you are upgrading from 4.0 to 4.2, APEX$_WS_ROWS_T1 is one of the object we automatically upgrade and shouldn't invalidate. Not sure what caused.