What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general.

Learn more

PRTG Network Monitor

Intuitive to Use. Easy to manage.
More than 500,000 users rely on Paessler PRTG every day. Find out how you can reduce cost, increase QoS and ease planning, as well.

Free Download

Top Tags

View all Tags

No or unexpected data displayed in PRTG live graphs. What can I do?



The data graphs in PRTG are empty or have gaps. They show strange values. What can I do?

cache graph graphs live prtg spikes

Created on May 28, 2013 1:49:45 PM by  Daniel Zobel [Product Manager]

Last change on May 28, 2013 1:50:06 PM by  Daniel Zobel [Product Manager]

1 Reply

Accepted Answer



This article applies to PRTG Network Monitor 12 or later

Graphs in PRTG

The normal Data view of PRTG offers up to four different graphs which can be displayed simultaneously. By default, these are

  • Live graph (last 2 hours)
  • 2 days graph
  • 30 days graph
  • 365 days graph

If monitoring data is available for the defined timespan each graph will display the respective data. However, in the event that a sensor’s live graph is not displaying any data, while all other graphs are, there are a couple of methods of solving this issue.

If All Sensor Graphs are Affected

Perform a cache recalculation. This will delete and re-calculate the graph cache used for the display in the web interface and the Enterprise Console.

For detailed instructions, please see: My PRTG has stopped graphing

If Individual Graphs are Affected

If you see unexpected high or incredibly low values in your graphs this may be the result of wrong data reported by your devices. A spike filter can remove these false peaks.

For detailed instructions, please see: Why do I see huge peaks or spikes in graphs for SNMP sensors?


If none of these procedures provides a solution please check your PRTG log files for any error messages, such as read / write errors or sensor counter changes which could account for the problem.

Created on May 28, 2013 2:00:08 PM by  Daniel Zobel [Product Manager]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.