2.1 RC4 upgrade error: Trying to access array offset on value of type null

[kirkvan]

Today, I upgraded from SMF 2.1 RC3 to SMF 2.1 RC4. Everything appears to be working well with the exception that my logs are showing recurrence of one cron.php error, which I've attached. Any debugging help would be appreciated.

[vbgamer45]

What PHP version?

[kirkvan]

Thanks for your reply. My server is running PHP 7.4.21.