This error message may be caused by an issue with the TFTP server program or the image may be wrong for the router.
If the router is a Cisco 3661 or 3662 series, it could have an Enterprise or a Telco chassis.
To resolve this issue, perform these steps:
Software versions cannot be interchanged between these two types of chassis and produce this error message. Before upgrading, identify the chassis type by issuing the show version command, as shown in this example:
3660#show version Cisco Internetwork Operating System Software IOS (tm) 3600 Software (C3660-TELCOENT-M), Version 12.1(5)T12, RELEASE SOFTWARE (fc1) TAC Support: http://www.cisco.com/tac Copyright (c) 1986-2002 by Cisco Systems, Inc. Compiled Mon 04-Feb-02 09:14 by ccai Image text-base: 0x60008960, data-base: 0x615C0000
ROM: System Bootstrap, Version 12.0(6r)T, RELEASE SOFTWARE (fc1)
crnetoheatn1a1 uptime is 3 days, 21 hours, 33 minutes System returned to ROM by reload System image file is "flash:c3660-telcoent-mz.121-5.T12.bin"
Cisco c3660-telco (R527x) processor (revision C0) with 254976K/7168K bytes of memory. Processor board ID JMX0620K1V0 R527x CPU at 225Mhz, Implementation 40, Rev 10.0, 2048KB L2 Cache Bridging software. X.25 software, Version 3.0.0. SuperLAT software (copyright 1990 by Meridian Technology Corp). TN3270 Emulation software.
3660 Chassis type: TELCO 2 FastEthernet/IEEE 802.3 interface(s) 2 Serial network interface(s) 8 Low-speed serial(sync/async) network interface(s) 64 terminal line(s) DRAM configuration is 64 bits wide with parity disabled. 125K bytes of non-volatile configuration memory. 65536K bytes of processor board System flash (Read/Write) 16384K bytes of processor board PCMCIA Slot1 flash (Read/Write)
Configuration register is 0x2102
This example shows that the router is a Telco chassis. Therefore, any non-Telco Cisco IOS Software image will not work on this router and the error message is displayed. In the same way, if it was an Enterprise chassis, a Telco Cisco IOS Software image would not work and the error message would be displayed.