Important Security Alert for the ArcGIS API for Flex/ArcGIS API for Silverlight

Esri has announced that they will be removing security policy files that are used by the ArcGIS API for Flex (January 26, 2021) and the ArcGIS API for Silverlight (October 12, 2021) from ArcGIS Online. This means that Flex and Silverlight apps will no longer be able to access any content / services from ArcGIS Online. Furthermore, due to security vulnerabilities associated with running Flash, Adobe no longer supports Flash as of 12/31/2020 and is taking steps to block Flash-based apps from running altogether.  


The ArcGIS API for Flex and ArcGIS API for Silverlight were retired in June 2016. However, Esri kept the policy files accessible so that developers who wanted to continue to use their deployed Flex and Silverlight apps could access content and services on ArcGIS Online. These policy files include:

Steps taken

These policy files are being removed in order to protect customers from security vulnerabilities; in line with Adobe, Microsoft, and major browser vendors:

What should you do?

Organizations should be taking several critical steps now, which include:

  • Line up a replacement app (ArcGIS API for JavaScript);
  • Make Flash removal a top priority;
  • Avoid downloading Flash from third-party sites after Adobe removes Flash from its website.

Esri is encouraging customers to migrate to a JavaScript-based app using the ArcGIS API for JavaScript. ArcGIS API for JavaScript is the focus of Esri’s web-based development and innovation, and far exceeds the capabilities of the older Flex and Silverlight APIs on many fronts.


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