I tried to connect my PayPal Express account on NationBuilder. The account saved without a problem, but when I go to make a donation instead of being redirected to PayPal, I receive the following error:
"Paypal API credentials are invalid. Please contact site administrator."
If there was an error connecting your PayPal account on NationBuilder, there are a few different problems that might be causing this:
1) Saving any settings in your payment processor without re-entering your API Username and Password. Any time you save payment processor settings, these two credentials are wiped from the user interface. If you haven't reentered them, saving the settings will save your credentials as blank values.
3) Having spaces before or after the API username, password, or signature credentials.
4) Using a PayPal Certificate instead of a Signature. If you have generated Certificate credentials, you will need to delete them and generate Signature credentials instead.
If you have confirmed that none of the above errors are to blame but you continue to receive the same errors, you can always delete your existing credentials and generate new ones.
You can view your API credentials in your PayPal Business account by going to Profile > Profile and settings > My selling tools > API Access (Update) > NVP/SOAP API integration (Manage API credentials).
If you haven't already done so, you will need to verify your account before requesting API credentials.
Complete and current information on how to use NationBuilder is available in the documentation section.