No module named 'sphinx.ext.pngmath'

[SIGISLV]

I didn't have any output error on installing pb_tool (via pip) but when I deploy the plugin it output this error. It seems to fail on the document creation step. I work on Win7 through the Network installer (OSGEO4W 64bit). My error output : Extension error: Could not import extension sphinx.ext.pngmath (exception: No module named 'sphinx.ext.pngmath')

My pip list output :

Package                       Version
----------------------- ---------
alabaster                     0.7.12
Babel                         2.6.0
certifi                       2018.8.24
chardet                       3.0.4
Click                         7.0
colorama                      0.4.1
coverage                      4.5.1
decorator                     4.3.0
docutils                      0.14
future                        0.16.0
GDAL                          2.4.1
httplib2                      0.11.3
idna                          2.7
imagesize                     1.1.0
ipython-genutils              0.2.0
Jinja2                        2.10
jsonschema                    2.6.0
jupyter-core                  4.4.0
MarkupSafe                    1.0
mock                          2.0.0
nbformat                      4.4.0
nose2                         0.8.0
numpy                         1.15.4
OWSLib                        0.17.0
packaging                     19.0
pb-tool                       3.0.6
pbr                           4.3.0
pip                           19.1.1
plotly                        3.3.0
psycopg2                      2.7.5
Pygments                      2.2.0
pyparsing                     2.4.0
pypiwin32                     223
pyproj                        1.9.6
PyQt5                         5.11.3
python-dateutil               2.7.5
pytz                          2018.7
pywin32                       224
PyYAML                        3.13
qgis2to3                      0.5
requests                      2.19.1
retrying                      1.3.3
setuptools                    41.0.1
sip                           4.19.14
six                           1.12.0
snowballstemmer               1.2.1
Sphinx                        2.0.1
sphinxcontrib-applehelp       1.0.1
sphinxcontrib-devhelp         1.0.1
sphinxcontrib-htmlhelp        1.0.2
sphinxcontrib-jsmath          1.0.1
sphinxcontrib-qthelp          1.0.2
sphinxcontrib-serializinghtml 1.1.3
traitlets                     4.3.2
urllib3                       1.23
xlwt                          1.3.0

[g-sherman]

sphinx.ext.pngmath was removed from sphinx. Upgrading it via pip should solve this issue