Paypal returns 400 Bad Request notice?

When testing SubscriptionBoss you may connect to PayPal and get the following error:

Paypal returns 400 Bad Request notice: Your browser sent a request that this server could not understand. Size of a request header field exceeds server limit.

This is a cookie issue and can be resolved by clearing your cookies.

We think it happens because you have an existing cookie laid down by a previous visit to PayPal maybe using a different PayPal account or where you have just been logged in to PayPal Sandbox.

In any case just clear your cookies and normal service will be resumed.

Note that your customers are very unlikely to run into this problem – unless they are PayPal developers – in which case they probably know what to do as this issue frequently comes up when testing applications that use the PayPal API


  1. Thanks. Clearing all cookies in past week helped. I tried clearing for selected PayPAl but that didn’t help.
    I assume this is a widespread issue site owners seem to have and likely to do with PayPal sandbox / test account for an eCom site in building stage. At least seems like that in my case.

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