I was getting this error too - I had the following at the top of my PHP page:
So, I made sure that I've got the latest versions of MySQLi, DataBridge and eCart installed, but opening and reapplying the recordset hasn't fixed the issue.
What it has done, however, is remove the error message I was receiving. I now have a blank white page (attached). I also attach what I assume is the updated rsobj.php file.
Incidentally, I'm testing using localhost in Windows 10 Pro and DWCC21.1 Build 15413
Hope you can help.