Symptom
After updating to WHMCS v8.6.0, users of the ResellerClub registrar module may encounter a TypeError when accessing a client's Domains tab in the admin area, when that account contains a domain transfer:
TypeError: Argument 1 passed to str_starts_with() must be of the type string, null given
Cause
The raaVerificationStartTime and endtime values returned by the ResellerClub API are null or non-numeric for this domain, when WHMCS expects to receive a timestamp.
Solution
Apply the 8.6.1 Maintenance Release via Utilities > Update WHMCS.
Hotfix
We have created a hotfix for WHMCS 8.6.0 to resolve the error:
https://whmcs.community/files/file/181-core-18272-correct-fatal-php-error-after-performing-a-resellerclub-transfer-in-the-admin-area/
Workaround
Switch your hosting environment to PHP 8.1.
The End! should you have any inquiries, we encourage you to reach out to the Vercaa Support Center without hesitation.