ArcGIS Online Web Connection Error: 401 Client Error: Unauthorized for URL

As of FME 2024.0, support for Esri ArcGIS Online (AGOL), ArcGIS Enterprise Portal, and ArcGIS Server Feature Services has transitioned to a unified approach using the new Esri ArcGIS Feature Service (Connector). This connector replaces the legacy reader/writer formats for each of the three services and also includes key transformers such as the ArcGISOnlineConnector, ArcGISAttachmentConnector, and ArcGISBranchVersionManager. 

Starting in FME 2026.0, the legacy formats will be hidden in the Quick Add menu. Instead, equivalent functionality is now provided by the downloadable Esri ArcGIS Connector package, available on FME Hub. The package can be installed directly through the Quick Add menu in FME Workbench, and once installed, the connector will appear in the Gallery as a unified interface for interacting with all three types of Esri ArcGIS Feature Services.

For details on this transition, including guidance on updating existing workspaces, please refer to the article: Working with Esri ArcGIS Feature Services in FME.

Consideration

I see the 401 Client Error: Unauthorized for URL error in my translation or job log.

Why This Happens

This is typically due to an expired ArcGIS Online connection or, if encountered on FME Flow, an invalid ArcGIS Online web service. 

How to Resolve It

Please see the steps below for FME Form and FME Flow. To prevent the ArcGIS Online web connection from expiring in the future, ensure a workspace using it is run at least every two weeks to refresh the underlying token; otherwise, you will need to reauthenticate the web connection in FME Workbench. 

FME Form

If the connection previously worked and has started to fail, try to reauthenticate it. To re-authenticate, select Tools in the top toolbar and then select FME Options. On the left-hand side of FME Options, select Web Connections. Find your ArcGIS Online Web connection, right-click on it, and select Reauthenticate.

In FME 2025.1+, FME Options is located under the Utilities menu.

If the workspace was authored in FME 2024.0 and earlier and is now opened in a newer version, you will need to update your Esri ArcGIS Feature Service connectors with the new FME Hub Package. Existing web connections also need to be updated.

ArcGIS Online tokens last 14 days by default, but an administrator can change this value. If you frequently need to reauthenticate, please check with your ArcGIS Online administrator

FME Flow

If you see this error on FME Flow, it is likely due to one of two reasons.

1. The ArcGIS Online Web Connection has Expired

The first reason is that the connection to ArcGIS Online has expired. If this happens, manually refresh the connection:

Go to the Web Connections page in FME Flow and click on the connection.


Click Authorize. If this button is greyed out, the web connection for FME Flow has not yet been configured. Please see the next section for instructions. 

2. The ArcGIS Online Web Connection has not been configured for FME Flow

If the web connection cannot be reauthorized because the button is disabled, as shown below, then the web connection is not set up properly for FME Flow. The instructions can be found in the article How to create ArcGIS Online Web Connection for FME Flow (OAuth 2.0)


If this does not work for you, you are likely encountering a network issue when connecting to ArcGIS Online. If you use a proxy, please verify that your proxy settings are set in the FME Flow UI. If you are still unable to connect, please submit a support case.