Quickfix
The Drupal nagios module reads the entries from the watchdog list. It happens that this crashes with an internal server error.
Recoverable fatal error: Object of class __PHP_Incomplete_Class could not be converted to string
To quickly fix that problem and analyze it further, the following change mitigates the effect:
526c526,528
< $message = str_replace((string) $key, $value, $message);
---
> if (!is_array($value) && gettype($value) !== "object") {
> $message = str_replace((string) $key, $value, $message);
> }