@chaowen guo Thanks for the additional details. We regret the inconvenience caused. This error occurs when there are parallel attempts to create App Service plans or if there are any previous pending operations in progress, and usually should not be persistent. Do you see any additional details about the error in the Activity logs?
Seems like you're facing this issue just with the southcentralus
region. While I couldn't find any known incidents on the Azure Status page, could you please check the Service Health dashboard for your Subscription that lists any health events that may have impacted your services?
If not, please retry creating a different App Service Plan and let us know what you see.