ESXi PXE boot fails with "Fatal error: 24 (TFTP Error)"
Article ID: 392554
Updated On:
Products
Issue/Introduction
Network booting ESXi via PXE may fail with "Fatal error: 24 (TFTP Error)" if the DHCPv4 server provides the bootfile path only in option 67, not in the DHCP header.
Some DHCP servers are configured to provide the bootfile path only in option 67, because option 67 allows for longer paths than the DHCP header.
Environment
ESXi 8.0.3 and earlier
Cause
In some configurations, the ESXi bootloader (the mboot component of esx-boot) looks for boot.cfg and possibly other files in (or relative to) the same directory that mboot itself was loaded from. In ESXi 8.0.3 and earlier, when loaded via PXE, mboot looks only in the DHCP header for the bootfile path that it was loaded from. If the bootfile path is not present there, mboot may fail to find boot.cfg or other necessary files.
Resolution
In ESXi 9.0.0, mboot looks in both option 67 and the DHCP header for the bootfile path. Because mboot is backward compatible, you can use an mboot binary from 9.0.0 or later to PXE boot older versions of ESXi such as 8.0.3 and earlier.
Additional Information
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