According to Microsoft support this error can be caused by
> A timing/concurrency issue where the PUT operations are happening
> about the same time for a single blob. The Put Block List operation
> writes a blob by specifying the list of block IDs that make up the
> blob. In order to be written as part of a blob, a block must have
> been successfully written to the server in a prior Put Block
> operation.
>
> Documentation reference:
>
> https://docs.microsoft.com/en-us/rest/api/storageservices/put-block
>
> This error can happen when doing concurrent upload commits after you
> have started the upload but before you commit. In that case, the
> upload fails. The application can retry this error or attempt some
> other recovery action based on the required scenario.
See: https://forum.rclone.org/t/error-while-syncing-with-azure-blob-storage-x-ms-error-code-invalidbloborblock/15561
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