# Hv.extension('bokeh') not working

**URL:** <https://discourse.holoviz.org/t/hv-extension-bokeh-not-working/7301>\
**Category:** hvPlot\
**Tags:** bokeh\
**Created:** [June 5, 2024, 1:57pm UTC](https://discourse.holoviz.org/t/hv-extension-bokeh-not-working/7301 "2024-06-05T13:57:05Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![nikhiljain20](https://discourse.holoviz.org/letter_avatar_proxy/v4/letter/n/7993a0/32.png) [@nikhiljain20](https://discourse.holoviz.org/u/nikhiljain20)\
**Post date:** [June 5, 2024, 1:57pm UTC](https://discourse.holoviz.org/t/hv-extension-bokeh-not-working/7301/1 "2024-06-05T13:57:05Z")

</div>

Hi, I am trying to plot a graph using holoviews but the bokeh extension is throwing me an error -

**Code** -

```python
import holoviews as hv
hv.extension('bokeh')

```

**Error** -

```auto
WARNING:param.notebook_extension: Holoviews bokeh extension could not be imported, it raised the following exception: ValueError('ClassSelector parameter None value must be an instance of (function, tuple), not <function size at 0x0000019DCD5443F0>.')
Unexpected exception formatting exception. Falling back to standard exception
Traceback (most recent call last):
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\interactiveshell.py", line 3550, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "C:\Users\nikhil.jain\AppData\Local\Temp\ipykernel_4136\3674089905.py", line 2, in <module>
    hv.extension('bokeh')
  File "C:\ProgramData\Anaconda3\lib\site-packages\param\parameterized.py", line 3631, in __new__
    return inst. __call__ (*args,**params)
  File "C:\ProgramData\Anaconda3\lib\site-packages\holoviews\ipython\ __init__.py", line 116, in __call__
    super(). __call__ (*args, **params)
  File "C:\ProgramData\Anaconda3\lib\site-packages\holoviews\util\ __init__.py", line 702, in __call__
    raise ImportError('None of the backends could be imported')
ImportError: None of the backends could be imported

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\interactiveshell.py", line 2144, in showtraceback
    stb = self.InteractiveTB.structured_traceback(
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 1435, in structured_traceback
    return FormattedTB.structured_traceback(
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 1326, in structured_traceback
    return VerboseTB.structured_traceback(
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 1173, in structured_traceback
    formatted_exception = self.format_exception_as_a_whole(etype, evalue, etb, number_of_lines_of_context,
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 1088, in format_exception_as_a_whole
    frames.append(self.format_record(record))
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 970, in format_record
    frame_info.lines, Colors, self.has_colors, lvals
  File "C:\Users\nikhil.jain\AppData\Roaming\Python\Python39\site-packages\IPython\core\ultratb.py", line 792, in lines
    return self._sd.lines
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\utils.py", line 145, in cached_property_wrapper
    value = obj. __dict__ [self.func. __name__] = self.func(obj)
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\core.py", line 698, in lines
    pieces = self.included_pieces
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\utils.py", line 145, in cached_property_wrapper
    value = obj. __dict__ [self.func. __name__] = self.func(obj)
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\core.py", line 645, in included_pieces
    scope_pieces = self.scope_pieces
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\utils.py", line 145, in cached_property_wrapper
    value = obj. __dict__ [self.func. __name__] = self.func(obj)
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\core.py", line 585, in scope_pieces
    for piece in self.source.pieces
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\utils.py", line 145, in cached_property_wrapper
    value = obj. __dict__ [self.func. __name__] = self.func(obj)
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\core.py", line 90, in pieces
    return list(self._clean_pieces())
  File "C:\ProgramData\Anaconda3\lib\site-packages\stack_data\core.py", line 114, in _clean_pieces
    raise AssertionError("Pieces mismatches: %s" % mismatches)
AssertionError: Pieces mismatches: [{660, 661}, {675, 676}, {688, 689}, {694, 695}]

```

**Version Details** -

 ![image](https://discourse.holoviz.org/uploads/default/original/2X/9/99ace98baed23a300744e6c34a037f02a3d201cf.png)

Can we help me with the error.

---

<div class="post-metadata">

**Author:** ![Marc](https://discourse.holoviz.org/user_avatar/discourse.holoviz.org/marc/32/24_2.png) [@Marc](https://discourse.holoviz.org/u/Marc)\
**Post date:** [June 7, 2024, 7:02pm UTC](https://discourse.holoviz.org/t/hv-extension-bokeh-not-working/7301/2 "2024-06-07T19:02:04Z")

</div>

Hi @nikhiljain20

Welcome to the community.

Try reporting this as a bug on Github.

---

<div class="post-metadata">

**Author:** ![maximlt](https://discourse.holoviz.org/user_avatar/discourse.holoviz.org/maximlt/32/2487_2.png) [@maximlt](https://discourse.holoviz.org/u/maximlt)\
**Post date:** [June 10, 2024, 12:50pm UTC](https://discourse.holoviz.org/t/hv-extension-bokeh-not-working/7301/3 "2024-06-10T12:50:11Z")

</div>

Can you please report your version of `param` , `ipython` and `stack-data`?