Troubleshooting FAQs

I have a license installed but can't run Houdini. What do I do?

Check to ensure you're trying to run the right product for the license you have. From the menu, select 'Houdini' to run Base Houdini (formerly known as Escape) and 'Houdini FX' to run Houdini FX (formerly known as Master). From the command-line, type 'basehoudini' to run Base Houdini, 'houdinifx' to run Houdini FX, and 'houdini' to run the program that you have licenses for, searching for Houdini FX licenses first and then Base Houdini licenses.

I lost my licenses – is there a way to get them back?

Sometimes the license file may get deleted, the disk may get reformatted, or the operating system may get reinstalled. In such cases, the license keys will be removed from the computer and you will need to obtain them again by following one of the methods below:

For Apprentice Users:

You can just download the software and install. You will be prompted to install non-commercial licenses when you start Houdini.

For Commercial and Indie Users:

Reinstall licenses on the same machine

If the License Administrator runs on a computer with the Internet connection:

  1. Start the License Administrator
  2. Choose File -> Install Licenses... and log in
  3. In the dialog window go to the "Licenses" tab
  4. Select the checkboxes for the licenses that you want to reinstall (this table lists all the missing non-expired licenses that match your computer name)
  5. Select the checkbox to reinstall the SERVER key as well (just in case it is missing too)
  6. Press install button

This should reinstall the selected licenses on your computer.

If the License Administrator runs on a computer with no Internet connection, you will need to reinstall the license keys manually:

  1. Log into with your username/password combination used for licensing
  2. Go to Manage Licenses and search for the machine that needs the license. Look your license history for every machine that has a license installation.
    Notice that each License ID (first column on the left hand side) contains a link.
  3. Click on the License ID to bring up a pop-up window, containing the keystrings
  4. Start the License Administrator and go to File->Manually Enter Keys. Copy and paste each keystring for the machine. Enter each keystring one line at a time. Note that you only need 1 SERVER keystring per machine. A keystring will begin with: SERVER, LICENSE, EXTEND, UPGRADE or INCREMENT.

Another manual way to rebuild your licenses file is to copy and paste the keystrings into a file called licenses, then install this file onto the machine.

The licenses file is located:

  • Windows: C:\Windows\keys\licenses
  • Linux: /usr/lib/sesi/licenses
  • Mac: /Library/Preferences/sesi/licenses

Make sure that you don't append any extensions to the filename (eg. .txt).

Reinstall licenses on a different machine

If you have replaced your machine and need your original licenses back (but they are tied to an old machine name), you will need to follow these steps:

  1. Rename your new machine to the original machine name for which the licenses were issued. Reboot if needed. Launch the Houdini License Administrator (hkey). Under File->Change License Server, make sure the server name is the one for which the licenses were issued; change it if it is not.
  2. Follow the section directly above (Reinstall licenses on the same machine).

If you reinstalled the keys automatically and now Houdini starts fine, then the problem is solved. However, if you want your new computer to have a new name then follow the instructions below.

If you reinstalled the keys manually, you will notice that this new machine won't be able to serve licenses yet because the server code is invalid. The server code is unique to each machine, and if you change machines then your server code will also change. If that's the case, you will need to return and reinstall the licenses again as described below. This will reinstall a valid SERVER key with the correct server code.

  1. Return your licenses to Side Effects Software (Refer the License Management section of the FAQ)
  2. Move your licenses file to a new file name (eg. licenses.old)
    Refer to the section "Where is the license file located on my machine?".
  3. If you want the machine to have a different machine name, you can change it now (and reboot if necessary). Otherwise, leave it as is.
  4. Re-install the returned licenses, which will also generate and install a new SERVER key for your new machine.

Now you should be able to start Houdini.

How can my clients on different subnets get a license from the server?

Ensure that your license IP masks are set to match your network type (class B, class C, or a specific list of subnets). If not, contact They will instruct you to return your licenses so that they can be rekeyed.

Obtaining licenses requires two processes. One being the actual "checkout" of the license, which is handled by the IP mask of the license installed. The second being the ability to read from the license server itself. This is controlled by the sesinetd.options file on the license server.

This file should contain the following: -V 2 -z 250000 -m

plus any other options that you would like (all on one line)

For example: A site has multiple subnets: +.+.*.*,192.168.*.*,10.*.*.*,172.*.*.*

The sesinetd.options file on the license server would contain:

-V 2 -z 250000 -m +.+. * . * ,192.168. * . * ,10. . . * ,172. * . * . *

This would allow clients on both subnets to checkout the license (through the IP mask in the keystring) and to read from the license server (through the sesinetd.options file).

The sesinetd.options file is located:

  • Linux: /usr/lib/sesi
  • Windows: C:\Windows\System32 (note that this file needs to be created first and placed here)
  • Mac: /Library/Frameworks/Houdini.framework/Versions/9.x.x/Resources/houdini/sbin

For more information about controlling the behaviour of sesinetd, please refer to the FAQ at -> Support -> FAQs -> License Management.

Where is the license file located on my machine?

The licenses file is located:

  • Windows: C:\Windows\keys\licenses
  • Linux: /usr/lib/sesi/licenses
  • Mac: /Library/Preferences/sesi/licenses

Make sure that you don't append any extensions to the filename (eg. .txt).

The License Administrator crashed during my license installation. When I try to install the licenses again, the License Administrator tells me that I don't have any entitlements. Where are they?

The License Administrator can redeem new Entitlements, reinstall missing Licenses and return existing installed Licenses. If the License Administrator crashes during your license installation, the licenses will show as being Redeemed on your account at Side Effects Software. Remember, redeemed means that the entitlements that previously could be installed on any computer have now been bound and transformed into actual licenses (LICENSE keys) tied to a particular computer.

If you find yourself in this situation, please refer to the question I lost my licenses – is there a way to get them back?

I just purchased Commercial licenses. I thought they were permanent licenses. Why do they expire in just a few weeks?

Once accounting verifies payment, your permanent licenses will be issued to you (in the form of extensions of your existing licenses). If you have any questions, please contact your account manager or

What should I do if the licenses have been installed but clients cannot check out any licenses?

Ensure that the netmask for the licenses is adequately open for your network. Netmasks are assigned by Side Effects Software and by default are a Class C network (+.+.+.*).

Also make sure that the clients can ping(see) the license server - by IP address and by hostname.

For example: ping hostname (where hostname is the name of the license server) or ping IP address (where IP address is the IP of the license server)

With Linux, an area to investigate is the /etc/hosts file. Ensure that you don't have anything appended to the line that contains the localhost. If you list your own hostname in the file, be sure to give it a separate IP address from the localhost (

In other words, ensure that you do not have a line containing: localhost.localdomain localhost myhostname

Sometimes, you will have a problematic line like: localhost yourmachinename

If you have the license server on your own machine, this shouldn't be a problem. However, for those who rely on a remote server, this could become an issue.

If you do have a line like one of the above, edit /etc/hosts to look like this: localhost.localdomain localhost 192.168.x.x yourmachine.yourdomain yourmachine

What do I do when the License Administrator (hkey) says that it has an "Invalid Server Key"?

The SERVER line in the licenses file has become invalid. This can happen when hardware changes are made to the machine hosting the licenses. To fix this problem, return your licenses (Refer to the section License Management of the FAQ). You will then either move the licenses file to a different name (perhaps licenses.old), or edit your licenses file. When you return your licenses, they are placed back onto your account as a new entitlement. You can now redeem your entitlements onto the same machine, and they will be converted into licenses along with a new SERVER keystring.

The licenses file is located:

  • Windows: C:\Windows\keys\licenses
  • Linux: /usr/lib/sesi/licenses
  • Mac: /Library/Preferences/sesi/licenses

Make sure that you don't append any extensions to the filename (eg. .txt).

What do I do if I receive the error: "Unable to connect to hserver for licence acquistion"?

This usually means that the client helper program, hserver, is not running.

On Windows, verify that you have the service HoudiniServer listed in Services and that it has started. You can go to Services through Control Panel->Administrative Tools. If it's not listed, ensure that there is a program called hserver.exe located in C:\Windows\system32.

On Linux, make sure that hserver is listed in the process list. If not, you can start it by typing hserver when you've sourced the Houdini environment.

Houdini is using a Houdini License Server (sesinetd.exe) and a Houdini License Client (hserver.exe) to verify its licensing. Houdini uses TCP/IP to communicate with these processes, and if it unable to connect to either of them, it prints error messages. There are a few reasons why Houdini is not able to connect to hserver. The most common reasons are:

  • Houdini License Server (sesinetd/sesinetd.exe) is not running
  • Houdini License Client (hserver/hserver.exe) is not running
  • The firewall blocks the communication on ports 1714 and 1715
  • If installing the license server and client on the same machine, it could be that Houdini wasn't installed using administrative privileges(root/Administrator).
What should I do if clients can no longer acquire licenses after rebooting the License Server?

Ensure that your License Server has a static IP address and all addresses are resolved correctly.

If the License Server itself uses DHCP to access the network, then it will not be able to serve licenses effectively. Either move the licenses to another License Server with a static IP address or assign a static IP address to the existing License Server.

I'm on KDE on Linux and Houdini seems to freeze on startup with no splashscreen or dialog popup.

The problem maybe a network port collision between KDEConnect and Houdini's licensing tools, namely ports 1714 and 1715.

You should be able to see the background process by running: ps -C kdeconnectd

The package is not required to run KDE, so you should be able to safely remove the package. On Debian-based Linux, this could be done by running the commands:

# do a dry-run first
sudo apt-get purge -s kdeconnect-plasma
# then, really remove the package
sudo apt-get purge kdeconnect-plasma/

Then, either restart your machine, or kill the background process manually: killall kdeconnectd

And now you should be able to run Houdini.

Why do I receive this error in the console?: NT_GeneratorThread::queueEvent eventqueuefull.Event dropped

This is due to using an older graphics card. Tell Houdini to use software OpenGL rather than hardware OpenGL. This is done by setting an environment variable:


What do I do if I'm having license trouble?

If you are experiencing difficulties with any part of the licensing process:

  1. Start the Houdini License Administrator (hkey)
  2. Under the View menu, select "Diagnostic Information"
  3. Save the file and attach it in an email addressed to

If you don't have a graphical display, you can type "sesictrl -f > file".

Attach the file to an email and send it to

sesictrl can be accessed:


  1. Go to the Start menu
  2. Go to Side Effects Software
  3. Go to Houdini 16.x.x
  4. Select Command Line Tools
  5. You now have access to sesictrl to run "sesictrl -f > file"


  • In a terminal, change to the directory where you have installed Houdini.
  • You will then type, "source houdini_setup".
  • You now have access to sesictrl to run "sesictrl -f > file".


/Library/Frameworks/Houdini.framework/Versions/16.x.x/Resources/houdini/sbin/sesictrl or

  1. Go to the Applications folder on the main system drive (Macintosh HD)
  2. Go to Houdini 9.x.x and double-click on the Houdini Shell.terminal program. This will source the Houdini environment for you. You now have access to sesictrl to run "sesictrl -f > file".
Are there any external resources where I can find more information?

Try these great references:

Houdini Forum