The descriptive flexfield with application name iAssets (IA) and name IA Request Headers (IA_REQUEST_HEADERS) is not frozen. Please contact your system administrator.
1) Navigate in regular Fixed Assets:
Setup > Financials > Flexfields > Descriptive > Segments
2) Query on:
Application = iAssets
Title = IA Request Headers
2) Click the "Freeze Flexfield Definition" checkbox and then hit the "Compile" button.
Additional note if the Flexfield View Generator is not spawning and it is required (in that this DFF may actually be used at some point) reference:
Unable to Compile a Descriptive Flexfield (DFF) : Flexfield View Generator Program is Not Spawned (Doc ID 1562495.1)
3) Next stop/start the webserver.
4) Once that is complete retest in iAssets again.