某些情况下，可能这些COS AP的其中某个part文件存在异常，导致无法转换成Mobility Express，此时会遇到如下的报错。
################################################################ 89.0% ################################################################ 89.6% ######################################################################## 100.0% Image downloaded, writing to flash... [*01/09/2019 14:41:33.9399] [*01/09/2019 14:41:33.9399] CAPWAP State: Discovery [*01/09/2019 14:41:33.9399] Discovery Request sent to 192.168.18.2, discovery type STATIC_CONFIG(1) [*01/09/2019 14:41:33.9499] Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0) do PREDOWNLOAD, part2 is active part tar: btldr.bin.lzma: not found in archive sh: CHECK_ME: unknown operand part.bin signature verification failure, exit the script Error: FILE_SIZE_ZERO, not updating ubi vol Error: '/etc/capwap-upgrade.sh PREDOWNLOAD' failure.
查看AP的版本情况。可以观察到AP的backup部分没有镜像文件，此时建议将AP的backup使用lightweight AP镜像填充。
AP1#show version Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. Cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706 This product contains cryptographic features and is subject to United States and local country laws governing import, export, transfer and use. Delivery of Cisco cryptographic products does not imply third-party authority to import, export, distribute or use encryption. Importers, exporters, distributors and users are responsible for compliance with U.S. and local country laws. By using this product you agree to comply with applicable laws and regulations. If you are unable to comply with U.S. and local laws, return this product immediately. A summary of U.S. laws governing Cisco cryptographic products may be found at: http://www.cisco.com/wwl/export/crypto/tool/stqrg.html If you require further assistance please contact us by sending email to export@cisco.com. This product contains some software licensed under the "GNU General Public License, version 2" provided with ABSOLUTELY NO WARRANTY under the terms of "GNU General Public License, version 2", available here: http://www.gnu.org/licenses/old-licenses/gpl-2.0.html This product contains some software licensed under the "GNU Library General Public License, version 2" provided with ABSOLUTELY NO WARRANTY under the terms of "GNU Library General Public License, version 2", available here: http://www.gnu.org/licenses/old-licenses/lgpl-2.0.html This product contains some software licensed under the "GNU Lesser General Public License, version 2.1" provided with ABSOLUTELY NO WARRANTY under the terms of "GNU Lesser General Public License, version 2.1", available here: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2015 by Cisco Systems, Inc. Compiled Fri Feb 24 22:26:41 PST 2017 ROM: Bootstrap program is U-Boot boot loader BOOTLDR: U-Boot boot loader Version 30 AP1 uptime is 0 days, 0 hours, 6 minutes Last reload time : Wed Jan 9 14:37:55 UTC 2019 Last reload reason : unknown cisco AIR-AP1815I-H-K9 ARMv7 Processor rev 5 (v7l) with 1015956/850284K bytes of memory. Processor board ID FGL2225XXXX AP Running Image : 8.3.111.0 Primary Boot Image : 8.3.111.0 Backup Boot Image : 0.0.0.0 1 Gigabit Ethernet interfaces 2 802.11 Radios Radio FW version : 8edf74e05d634a962e683454e8fc1be2 NSS FW version : not available
将AP的backup区域刷一个镜像，这里以Release 8.5.182为例。
LAP#archive download-sw /reload tftp://192.168.18.2/ap1g5-k9w8-tar.153-3.JF15.tar
########### 15.4%[*01/09/2019 14:52:45.2299]
[*01/09/2019 14:52:45.2299] CAPWAP State: Discovery
[*01/09/2019 14:52:45.2399] Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0)
########################################### 60.8%[*01/09/2019 14:52:54.7299]
[*01/09/2019 14:52:54.7299] CAPWAP State: Discovery
[*01/09/2019 14:52:54.7499] Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0)
######################################################################## 100.0%
待AP重启后，可以看到两个part都具有镜像文件。
AP Running Image : 8.5.182.0 Primary Boot Image : 8.5.182.0 Backup Boot Image : 8.3.111.0 1 Gigabit Ethernet interfaces 2 802.11 Radios Radio FW version : 8fd6300a6e46b2e512e1452959ec6814 NSS FW version : not available
等到这种情况下的时候，我们再使用ap-type mobility-express命令去完成ME模式的转换。
LAP#ap-type mobility-express tftp://192.168.1.2/AIR-AP1815-K9-ME-8-5-182-0.tar
待AP镜像获取完毕，即可启动成ME的系统。
The system is going down NOW! Sent SIGTERM to all processes Sent SIGKILL to all processes Requesting system reboot99] [08/30/2021 05:05:24.3599] reboot: Restart Board type: AP1815I smem ram ptable found: ver: 1 len: 3 U-Boot 2012.07 (btldr release 37) (Jan 07 2021 - 10:16:04) This product contains some software licensed under the "GNU General Public License, version 2" provided with ABSOLUTELY NO WARRANTY under the terms of "GNU General Public License, version 2", available here: http://www.gnu.org/licenses/old-licenses/gpl-2.0.html DRAM: 1022 MiB Nand: Detected ONFI Macronix NAND 256MiB 3,3V 8-bit NAND ECC=4 ECC_THRESHOLD(NAND ECC-1)=3 SF: Detected W25Q32 with page size 4 KiB, total 4 MiB MFG data loaded Scanning shenv data blocks Total valid parts=4 Active shenv part[0:1], write_counter=6 machid: 8010001 Net: MAC0 addr:50:2f:a8:96:b6:d0 AR8033 PHY 0 PHY ID1: 0x4d PHY ID2: 0xd072 ipq40xx_ess_sw_init done Auto boot mode, use bootipq directly Hit ESC key to stop autoboot: 0 Specified BOOT: part2 Booting from part2 Read 1024 bytes from volume part2 to 88000000 Read 22070735 bytes from volume part2 to 88000000 Signature returns 0 Image signing verification success, continue to run... bootm 0x88000400 ## Booting kernel from Legacy Image at 88000400 ... ## Loading init Ramdisk from multi component Legacy Image at 88000400 ... ## Flattened Device Tree from multi component Image at 88000400 Booting using the fdt at 0x89503188 Loading Ramdisk to 9ecc6000, end 9ffff658 ... OK Loading Device Tree to 9ecba000, end 9ecc5c46 ... OK no such device nand0 Using machid 0x8010001 from environment Starting image ...
此方法可以尝试解决LAP无法直接升级为ME模式（如最开始的报错）的情况。