Canon EOS-1D X Instruction Manual page 96

Handling Error Messages
73: Could not synchronize the time
Are you following the correct procedure to establish a connection

between the master and slave cameras?

Operate the master and slave cameras by following the correct
instructions (p.80-82).
81: Wired LAN connection lost
Is the LAN cable securely connected?


Reconnect the LAN cable between the camera and server. Because
the cable may be severed, try using another cable to connect the
devices.
Is the hub or router on?

 Turn on the hub or router.
Is the server on?


Turn the server on. The server may have been turned off because of
an energy-saving mode.
91: Other error
An error other than error number 11 to 81 has occurred.


Turn the camera's power switch off and on.
.
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