Werk #22470: WMI checks: report a counter frequency of zero instead of crashing
| Component | Checks & agents | ||||||
| Title | WMI checks: report a counter frequency of zero instead of crashing | ||||||
| Date | Sep 22, 2026 | ||||||
| Level | Trivial Change | ||||||
| Class | Bug Fix | ||||||
| Compatibility | Compatible - no manual interaction needed | ||||||
| Checkmk versions & editions |
|
If a Windows host reported a performance counter frequency of 0, every check
reading a per-second counter from that host went UNKNOWN with
ZeroDivisionError: float division by zero and produced a crash report instead
of a result. Seen on MS Exchange Availability Service, but any WMI based
check reading a rate was affected.
Checkmk already tolerated a missing frequency, but a frequency reported as the
text 0 passed that check and then divided by zero.
The affected result now reports UNKNOWN and names the cause, for example
Requests: cannot compute a rate, the host reported a counter frequency of 0.
The other results of the service are produced as before, so the rest of the
host's data keeps being monitored.
A frequency of 0 means the host's WMI provider is delivering a broken counter block; Checkmk cannot derive a rate from it and deliberately reports that rather than inventing a value.