If a plugin send unknown fields munin stops updating the HTML pages.

[mvaled]

I have created several plugins that (mistakenly) were sending a "description" field per each variable in its configuration. Example:

cpu.label CPU%
cpu.description The amount of CPU used by the process.

This makes munin-update to issue several warnings, and stops generating the PNGs and HTML pages.

This issue was discussed on the mailing list