FYI - I just had this same issue:

Brand new RPI 3+
Brand new SD card image
Updated/ upgraded and then got the 404 error page on the desktop

Tried the above command and it ended with:
Setting up indi-sbig (2.1-3) xxx
Processing triggers for ...
...
Processing triggers for initramfs-tools (0.133+deb10u1) ...
Errors were encountered while processing:
libraspberrypi0
libraspberrypi-doc
libraspberrypi-bin
libraspberrypi-doc
rpi-eeprom

did a restart and the web based interface worked... just like jdain said it would!

Thanks for asking/ solving this issue so quickly...

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