Track 4 Upgrade

I just completed 4.211.64-2 - 4.211.64-3 upgrade. I noticed this error appearing several times throughout the process:

PHP Warning: PHP Startup: Unable to load dynamic library ‘/usr/lib/php/modules/’ - /usr/lib/php/modules/ cannot open shared object file: No such file or directory in Unknown on line 0

Everything seems to be working OK after the upgrade so wonder if the error is significant?