# FAQ And Troubleshooting

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### Optical Flares does not start / can't find the license / is crashing / producing strange things, what can i do?

Check out this FAQ, we provide helpful installation and trouble shooting tips here. The most important step for trouble shooting and finding issues is to check the Optical Flare debug log. The debug output will be prompted to the console. You have to enable debug output for that by setting the environment variable OPTICAL\_FLARES\_VERBOSE\_CONSOLE to true. (Mac users please note that the shell is hidden by default on Mac, you have to start Nuke from the command line in this case)<br>

### How do i set an environment variable?

Environment variables provide an extremely convenient way to control application behaviour, especially in bigger environments. There are numerous ways how to set them and they are different on each operating system. The easiest way is to let nuke control your environment variables specifically for Nuke. You can set this by editing your nuke.py configuration file:

\
os.environ\['OPTICAL\_FLARES\_VARIABLE'] = 'content'<br>

### Optical Flares can't detect the license but i have installed it correctly. What should i do?

Check the output of your optical flares debug log. It will show you the exact location of your license file. If it is there and can be accessed, it might be broken. Please contact support.<br>

### I have a render farm and multiple render farm licenses but they are all stored on the same server. Now the render farm version is a separate plugin, how do i distinguish both versions.

You have to configure nuke accordingly so that it loads up the correct plugin version. You can do this by amending your init.py file in this way:

{% hint style="info" %}
if nuke.env\['gui']:

&#x20;    nuke.pluginAddPath(path/to/full')

else:

&#x20;    nuke.pluginAddPath('path/to/farm')
{% endhint %}

**Note**: You can do the same for different license files by altering the license path variable instead.<br>

### If i start Nuke on Windows manually all runs fine, but if i open a .nk script, i don't get a valid license anymore.

Nuke is changing it's home directory to the .nk file and thus licensing renders invalid. You have to adjust your OPTICAL\_FLARES\_LICENSE\_PATH to a hardwired license location.<br>

### The Optical Flares Interface / UI does not Open when clicking the Options button

This may have to do with the Display value. The first thing to do is check the DISPLAY var on your machine. To find out that value, you can enter this variable:

**echo $DISPLAY**&#x20;

Once you know that value, you can set an env variable for Optical Flares to whatever that value is. By default, Optical Flares uses :0 but your Linux XServer may be running in a different one.

Here is the env variable you can set for Optical Flares:

**OPTICAL\_FLARES\_DISPLAY\_NAME**&#x20;

For reference, it would look like the below example only instead of 1, you would change the value to what your server is using.

OPTICAL\_FLARES\_DISPLAY\_NAME=:1

Example of how to set it if using Nuke init.py file:

[**os.environ\["OPTICAL\_FLARES\_DISPLAY\_NAME"\]=":100"**](#user-content-fn-1)[^1]

[^1]: