Hi Pratik,
I think the issue here is that a non-null value is being sent in the clientCustomerId header in your requests. Looking at the PHP library the
Configuration class should return a null value if a particular configuration value isn't present. Is it possible that in your adsapi_php.ini configuration file there's a non-null value for clientCustomerId that might be making its way into the request header?
Thanks,
Ben, Google Ads API Team

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