It seems your application don't have access to the storage account , please validate below :
- The application which is trying to do this operation , check if it has got all the required permissions
- If the application is making use of SAS Key , please check if the SAS key is still valid or not
- Try to regenerate the SAS key with new expiration date
- Check if the storage account is behind the VNET and firewall is enabled
- If the Firewall is enabled for storage account , did you create any private Link pointing to the VNET in which your application is deployed.
Let us know how it goes...
Regards,
Shiva.