can't perform this operation for unregistered loader type

Ran into the same error using pyinstaller.

This should solve your problem and the problem of not finding jinja2 that will follow:

edit the file: your-python-env\Lib\site-packages\bokeh\core\

(nb: change your-python-env to wherever you've installed python)

and change the import statements from:

import json

from jinja2 import Environment, PackageLoader, Markup

to the following:

import json
import sys, os
import bokeh.core    
from jinja2 import Environment, FileSystemLoader, Markup

Next, find the line where it says:

_env = Environment(loader=PackageLoader('bokeh.core', '_templates'))

comment this out and replace it with this code:

# _env = Environment(loader=PackageLoader('bokeh.core', '_templates'))

if getattr(sys, 'frozen', False):
        # we are running in a bundle        
        templatedir = sys._MEIPASS
        # we are running in a normal Python environment
        templatedir = os.path.dirname(bokeh.core.__file__)

_env = Environment(loader=FileSystemLoader(templatedir + '\\_templates'))

(adapted from:

What this does is that when the code is frozen, it redirects the jinja2 looking to sys._MEIPASS (which is the folder where your distribution is). Specifically it looks for the jinja2 templates at sys._MEIPASS_templates. When frozen, the file points to the wrong location, hence the original problem.

So now, we have to make sure the jinja2 files end up at the _templates folder. To do this we edit the pyinstaller .spec. This works for compiling to one directory or one file. Edit the datas in your .spec file to:

a = Analysis([''],

What this does is it gets the contents of the core_template folder and copies it to dist_templates. Which is exactly where we've pointed the to look for the jinja2 files.

This resolved the problem for me with pyinstaller==3.3.1, bokeh==0.12.9 and jinja2==2.10.

Bokeh relies heavily on Jinja2 for its operation. There appears to be a problem between Jinja and Pyinstaller:

So this may simply not be possible unless these downstream issues have been resolved.