Hi @Eren Cakmak , Thanks for posting on Microsoft Q&A.
Based on my research, I found that this error can occur if you have already configured a witness (FileShare or any other) and then you try to change the Witness to Cloud Share Witness. It fails with the error - "Verify the Azure storage account name, storage account type, storage account key, and network connectivity over HTTPS".
To resolve this, simply remove existing witness and then try to add the Cloud share witness.
Because there was already a physical Witness Disk configured for the Failover Cluster, the Cloud Witness Disk wizard could not proceed to successfully add a Cloud Witness Disk. Removing the already configured physical witness disk and running the Cloud Witness Disk wizard again should help.
Hope this helps. If you are still seeing this issue, please let me know in the comments and I would be happy to investigate further.
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