Azure logic apps SFTP Copy File action breaks with some SAS Urls

Question

I was experiencing a problem with a logic app which

1. Used the Create SAS URI by path action to get a SAS-enabled URL for a blob in a storage account

2. Used the SFTP copy file action to copy the file to an SFTP connector

The process would fail roughly 50% of the time with an authorization error when trying to fetch the blob from storage.

"actions": {
    "Create_SAS_URI_by_path": {
        "inputs": {
            "body": {
                "Permissions": "Read"
            },
            "host": {
                "connection": {
                    "name": "@parameters('$connections')['azureblob']['connectionId']"
                }
            },
            "method": "post",
            "path": "/datasets/default/CreateSharedLinkByPath",
            "queries": {
                "path": "/container-name/SomeSourceFile.csv"
            }
        },
        "runAfter": {},
        "type": "ApiConnection"
    },    
    "Copy_file": {
        "inputs": {
            "host": {
                "connection": {
                    "name": "@parameters('$connections')['sftp']['connectionId']"
                }
            },
            "method": "post",
            "path": "/datasets/default/copyFile",
            "queries": {
                "destination": "testing-if-works.csv",
                "overwrite": true,
                "source": "@{body('Create_SAS_URI_by_path')?['WebUrl']}"
            }
        },
        "runAfter": {
            "Create_SAS_URI_by_path": [
                "Succeeded"
            ]
        },
        "type": "ApiConnection"
    }
}

Answer 1

This bug has been fixed in SFTP connector. To make it work, please create a new logic app with appropriate actions.

Answer 2

The SFTP connector has a bug which causes it to fail if a SAS Url has a plus sign (%2B) in the signature, presumably due to how the connector code handles the URL when it tries to GET the blob by Url. The fix is to double-encode the plus sign:

"source": "@{replace(body('Create_SAS_URI_by_path')?['WebUrl'], '%2B', '%252B')}"

I'd report this to Microsoft, but can't find the Github repo for the connector. Hope this helps someone else in the future.