Warning, do not attempt to upgrade a WR21 that is part of the Beta program with 5.139 firmware via FTP or the web UI upgrade facility. The flash structure has changed between firmware versions 5.138 and 5.139 and an upgrade can normally only be made by Flashwriter.

It is necessary to use the special .all file in the "upgrade_flash_structure" folder to upgrade to version 5.139 from any earlier version.

http://transport.digi.com/digi/firmware/flashwriter/5139/WR21/upgrade_flash_structure/

A serial cable is required during this upgrade.