Test connection Connection manger in SSIS to the azure storage using access key succeeded. While copying data using Flexible file task in SSIS throwing an error "[Flexible File Task] Error: Could not load file or assembly 'Microsoft.Azure.Storage.Common, Version=11.1.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified." The Folder paths and filenames everything seems correct. What would be reason?
Azure.Storage.Common nuget package getting removed as soon as I close script task to run the package and throws same error
This is a spurious error message. It is a security error
Go to your storage account, under Settings, Configuration, change Minimum TLS version from 1.2 to 1.0.
Or if you want to keep the 1.2 channel, you will need to modify the registry on the computers that may run the SSIS package
https://billfellows.blogspot.com/2022/01/ssis-azure-feature-pack-and-flexible.html
Furthermore, based on your comment referencing nuget. Nuget and SSIS Script Tasks and Components do not mix. The Developer experience of crafting a script knows how to use the nuget package manager to acquire the assemblies. However, when you close the script/component editor, those bits are not serialized with the project. When the package executes, there is no part of the run-time engine that identifies this assembly is from a nuget source and therefore, we need to download those bits. Instead, it fails when it cannot find the reference.
It still seems weird that a script task/component is throwing an exception about the azure bits as the Flexible File Task is not a script. https://learn.microsoft.com/en-us/sql/integration-services/control-flow/flexible-file-task?view=sql-server-ver15