Invalid CSR when using Let's Encrypt web tools

Question

I've created a CSR using IIS. When I paste the text here...

https://www.sslshopper.com/csr-decoder.html

... it validates correctly.

But when I use the Let's Encrypt tools here...

https://zerossl.com/free-ssl/#crt

https://gethttpsforfree.com/

... both of these tools say that the CSR is invalid.

Why is this?

Answer 1

I needed to remove "New" from the text

-----BEGIN NEW CERTIFICATE REQUEST-----

and

-----END NEW CERTIFICATE REQUEST-----

The second of the tools was using a Regex which wasn't looking for that word.