If you wish to upgrade your firmware from OpenWrt without resetting to stock first then you might get:
The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform.
.bin files are for flashing from a stock firmware.
.trx files are for flashing from OpenWrt. To convert from
.trx, strip the 32-byte header from the
dd if=openwrt-10.03.1-brcm47xx-wrt150n-squashfs.bin bs=32 skip=1 of=openwrt-10.03.1-brcm47xx-wrt150n-squashfs.trx
IMPORTANT: Verify that the output file is only 32 bytes smaller than the input file and that the
.trx file begins with
hd /tmp/openwrt-10.03.1-brcm47xx-wrt150n-squashfs.trx | head
NOTE: However, the
.trx file that is offered for download is identical to the file that you produce with
dd, so use the official
.trx instead of this method if possible!