Hi Prem - Thanks for reaching out.
Based on the exception, the SPN seem to be missing some permission in order to perform the write operation.
Are you making of RBAC or ACLs? If ACL's, you can try using RBAC with role such as Storage blob Data Contributor that shall help in the isolation.
Another pointer to check is if there are any networking level restriction on the account level?
Please let us know if you have any further queries. I’m happy to assist you further.
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