Receiving message : - Bad property assignment: --prop:Any ideas?:(

looks like an empty property assignment, did you use any command line parameters or did you use a ~/.fgfsrc file?Also, please state what platform you're using and whether you are using fgrun to launch FlightGear. Apart from that, this is usually not really a critical warning, as long as the corresponding parameter isn't meant to enable/disable crucial options.

Thanks. Resolved problem. As you said a blank field required deletion. Stupididy, actually!!