SSL Certificate validated by browser but can't fetch

Question

I created a Symfony API using API Platform. I put this API in production and it is easily accessible via a browser with the address https : // mydomain.net/api

However, when trying to fetch the api through my reactjs app, I got no response. I tried through postman and it looks like the ssl certificate is having a problem. By disabling certificate verification on postman, everything works fine.

I don't understand the problem because on any browser the API says "Secure Connection. Your connection to this site is secure. Verified by DigiCert Inc". My SSL certificate is provided by Ionos.

Thank you in advance for your help.

Answer 1

Problem solved, I had not added the intermediate certificate in production. Interesting to see that it is not necessary on a browser but is necessary to make API calls.