PayPal gateway has rejected request. Security header is not valid (#10002: Security error Magento

Question

up the pay-pal advance in magento . I have fill all the credentials in magento admin . BUt when i go to frontend and click pay-pal button it gives

Pa

Answer 1

I got the same problem and found the problem is

• I type the API signature character by charter, the character "I" is similar to "l"
• As there are multiple "I" in the signature, I have to tested one by one via the link mentioned by Vimalnath.
• Then damn it, it works.

Therefore, copy is a better way while being careful about the spaces at the front or end.