While the other answers works, it does not fix the core issue which might come back later. Since I had the same error at work, I think this would help:
The error unable to find valid certification path to requested target indicate that Eclipse failed to access the site using HTTPS because it can't recognize the certificate for various reasons:
- This might be a self signed certificate (highly doubtful for gradle.org)
- The CA COMODO ECC Domain Validation Secure Server CA 2 is not valid;
You can check which Root CA is in your trust store using the Java panel: if it is missing, then you get your explanation.
- You may add it to your trust store using the Java CPL. You need to export the certificate first in your browser.
- You may add the certificate of the website but I would not recommend it: you will have problems with website using the same CA.
- You could try to update your JDK to latest JDK8/11, but be wary that Eclipse might not use the JRE/JDK you expect it to use; for that, you'll need to use the
-vm
launch parameter.