An Azure service that is used to manage and protect cryptographic keys and other secrets used by cloud apps and services.
Hello @Developer ,
Thanks for the question and using MS Q&A platform.
As I understand, you are trying to use Key Vault certificate in ADF Web activity, but when you try to choose a certificate, the list gives fail to load error.
This can happen when the Data Factory does not have permission to List / Get certificate in the Key Vault.
Go to the Key vault Access Policies. Add a new policy. Pictures below.

You want Get & List permissions for Certificate if you only use certificate. If you use Secrets and Keys, choose those too.
List permission lets you see the choices. Get permission lets you retrieve the value.
Decrypt and Unwrap are if you put extra security on your stuff. Not always necessary.

For "Principal", choose your Data Factory / Synapse.
After you create this access policy, wait 1 - 5 minutes and try again listing the certificates in the Factory.

Hmm, Maybe need secrets not certificates?
Please do let me if you have any queries.
Thanks
Martin
- Please don't forget to click on
or upvote
button whenever the information provided helps you. Original posters help the community find answers faster by identifying the correct answer. Here is how - Want a reminder to come back and check responses? Here is how to subscribe to a notification
- If you are interested in joining the VM program and help shape the future of Q&A: Here is how you can be part of Q&A Volunteer Moderators