Hello PRTG Support.

We have an HTTP Advanced sensor that performs a GET on a URL that returns some text.

When the page is indicating there has been an error, the text "ERROR " will appear, followed by a number of words in all uppercase indicating the issue.

When the page is indicating there is *no* problem, the "ERROR " and subsequent text is not present. For reference, there are a number of message combinations that can follow the "ERROR " text.

I am trying to return the all of the ERROR text into an alert that is to be emailed out. I have notifications successfully firing for the error condition and the sensor is setup as follows:

1. Check for Existing Key Words (Negative) = Enabled

2. Response Must Not Include = ERROR[A-Z\s]+(?!\d)

3. For Keyword Search Use = Regular Expression

However, when the notifications fire, we receive the following in the email:

"Last Message Error: String found [ERROR[A-Z\s]+(?!\d)]"

Why doesn't the "Last Message" contain the text that the regex matched, as opposed to the regex itself...this seems very not useful.

Am I missing something?

Many thanks for your time on this.

Article Comments

Dear Kevin,

What message is displayed in the sensor message field?


Oct, 2014 - Permalink

Hello Felix,

When the sensor is in a "Down" state, the Notification displays "Error: String found [ERROR[A-Z\s]+(?!\d)]" in the "Last Message" field (on both the webpage and in the Notification).

When the sensor is in an "Up" state, the Notification displays "OK" in the "Last Message" field (on both the webpage and in the Notification).

Note that "ERROR[A-Z\s]+(?!\d)" is the value of the regex as previously mentioned. My question is, shouldn't the regex return the text matched by the regex, in this context, instead of the regex itself?

Also (meant to put this in the original post) we are using the latest version of PRTG as of the date of this posting -- 14.3.11.2954.

Again, many thanks for the feedback.


Oct, 2014 - Permalink

Hello Kevin,

Thank you for your clarification. As this is not possible to do with the current version of PRTG, I'll forward the wish to display the text message instead of the regex pattern as a feature request for future versions of PRTG.

Best regards


Oct, 2014 - Permalink

Many thanks and please do. Again, we feel this behavior is vcounter intuitive and leads to confusion. Further, it would greatly increase the usefulness of a Notification originating from a regex-matching Sensor.

Again, thanks for your time.


Oct, 2014 - Permalink