Troubleshooting KRC Connection Failure


  • Kaseya Remote Control (KRC) sessions persistently fail to connect

  • KRC sessions are persistently dropped

  • KRC viewer reports “connected” but the remote desktop is not displayed


There is no universal cause, but common issues include: -

  • a firewall blocks WebSocket connections between viewer machine and kserver, or between agent machine and kserver

  • a content filtering service on a firewall blocks packets it does not recognize

  • in some earlier builds of VSA R7, the viewer would attempt connection over incorrect port


To isolate the source of the problem, perform these basic troubleshooting steps: -

1) test connection to several different agents on different remote networks, in case the problem is related to a specific agent or network location

2) test connection from a different network location

on-premises customers only: -

3) test connecting to the kserver agent

4) log onto the kserver console (using another remote desktop tool such as RDP), log onto Kaseya using HTTP(s)://localhost, and from there try to connect to external agents using KRC

5)ensure VSA server has the latest patches and uninstall Kaseya Remote Control from the “viewer” machine (latest build of the viewer will be installed on a new connection

Depending on the results of the above tests, check the firewall logs and configurations in the affected locations (viewer, agent, or kserver) for the following: -

  • are any packets dropped: -

- between viewer and kserver on the same port that you access the VSA web interface with (usually 80 or 443)

- between agent and kserver on the agent check-in port (usually 5721)

- between agent or viewer and on port 3478 (TCP or UDP)

  • is there any content level filtering enabled? If so, temporarily disable it and re-test KRC.
  • is HTTPS inspection or a similar service enabled on the firewall? If so, click here for further details


If further assistance is needed, please provide Kaseya Support with the following information: -

1) exact description of problem condition, with a screenshot of any on-screen error message or unexpected behavior

2) details of steps mentioned above, and any other troubleshooting steps are taken so far

3) KRC logs from viewer and agent machines, captured just after reproducing the problem

Agent Logs

  • Windows XP and 2003: C:\Documents and Settings\All Users\Application Data\Kaseya\Log

  • Windows Vista and later: C:\ProgramData\Kaseya\Log

  • OS X: /Library/Logs/com.kaseya

Viewer Logs

  • Windows XP and 2003: C:\Documents and Settings\<user>\Application Data\Kaseya\Log

  • Windows Vista and later: C:\Users\<user>\AppData\Local\Kaseya\Log

  • OS X: /Users/<user>/Library/Logs/com.kaseya


Kaseya VSA R7 and above

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