diff --git a/conda.recipe/meta.yaml b/conda.recipe/meta.yaml
index 790148875..86c5f21c4 100755
--- a/conda.recipe/meta.yaml
+++ b/conda.recipe/meta.yaml
@@ -11,7 +11,7 @@ requirements:
     - "python>=3.10, <3.13"
     - "numpy>=1.26"
     - "pandas>=2.2"
-    - "bokeh>=2.4"
+    - "bokeh>=3.6"
     - "paramtools>=0.19.0"
     - numba
     - curl
diff --git a/environment.yml b/environment.yml
index 1d18ee34f..d10883225 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,7 +5,7 @@ dependencies:
 - "python>=3.10, <3.13"
 - "numpy>=1.26"
 - "pandas>=2.2"
-- "bokeh>=2.4"
+- "bokeh>=3.6"
 - numba
 - curl
 - setuptools
diff --git a/setup.py b/setup.py
index 6582586ef..35cc33104 100644
--- a/setup.py
+++ b/setup.py
@@ -4,16 +4,15 @@
 
 from setuptools import setup
 
-with open("README.md") as f:
+with open("README.md", "r", encoding="utf-8") as f:
     longdesc = f.read()
 
 VERSION = "4.4.0"
 
 config = {
-    "description": "Tax Calculator",
+    "description": "Tax-Calculator",
     "url": "https://github.com/PSLmodels/Tax-Calculator",
     "download_url": "https://github.com/PSLmodels/Tax-Calculator",
-    "description": "taxcalc",
     "long_description_content_type": "text/markdown",
     "long_description": longdesc,
     "version": VERSION,
@@ -24,7 +23,7 @@
     "install_requires": [
         "numpy>=1.26",
         "pandas>=2.2",
-        "bokeh>=2.4",
+        "bokeh>=3.6",
         "numba",
         "paramtools>=0.19.0",
     ],
diff --git a/taxcalc.egg-info/PKG-INFO b/taxcalc.egg-info/PKG-INFO
index ad273b718..48da0e9ce 100644
--- a/taxcalc.egg-info/PKG-INFO
+++ b/taxcalc.egg-info/PKG-INFO
@@ -20,7 +20,7 @@ Description-Content-Type: text/markdown
 License-File: LICENSE
 Requires-Dist: numpy>=1.26
 Requires-Dist: pandas>=2.2
-Requires-Dist: bokeh>=2.4
+Requires-Dist: bokeh>=3.6
 Requires-Dist: numba
 Requires-Dist: paramtools>=0.19.0
 
diff --git a/taxcalc.egg-info/requires.txt b/taxcalc.egg-info/requires.txt
index 2cda2894d..e78702db6 100644
--- a/taxcalc.egg-info/requires.txt
+++ b/taxcalc.egg-info/requires.txt
@@ -1,5 +1,5 @@
 numpy>=1.26
 pandas>=2.2
-bokeh>=2.4
+bokeh>=3.6
 numba
 paramtools>=0.19.0
diff --git a/taxcalc/calculator.py b/taxcalc/calculator.py
index b5b93c7b7..cbce15154 100644
--- a/taxcalc/calculator.py
+++ b/taxcalc/calculator.py
@@ -1043,9 +1043,6 @@ def pch_graph(self, calc, pop_quantiles=False):
         # construct data for graph
         data = pch_graph_data(vdf, year=self.current_year,
                               pop_quantiles=pop_quantiles)
-        del vdf
-        del vdf1
-        del vdf2
         # construct figure from data
         fig = pch_graph_plot(data,
                              width=850,
@@ -1053,7 +1050,6 @@ def pch_graph(self, calc, pop_quantiles=False):
                              xlabel='',
                              ylabel='',
                              title='')
-        del data
         return fig
 
     REQUIRED_REFORM_KEYS = set(['policy'])
diff --git a/taxcalc/tests/test_data.py b/taxcalc/tests/test_data.py
index 68254b9ef..5530ed7b8 100644
--- a/taxcalc/tests/test_data.py
+++ b/taxcalc/tests/test_data.py
@@ -81,7 +81,7 @@ def __init__(self, data, start_year, gfactors, weights):
         def _extrapolate(self, year):
             val = getattr(self, 'e00300')
             setattr(
-                self, 'e00300', val* self.gfactors.factor_value('AINTS', year)
+                self, 'e00300', val * self.gfactors.factor_value('AINTS', year)
             )
 
     # test Recs class for incorrect instantiation
diff --git a/taxcalc/tests/test_decorators.py b/taxcalc/tests/test_decorators.py
index a79314e29..86253a3e7 100644
--- a/taxcalc/tests/test_decorators.py
+++ b/taxcalc/tests/test_decorators.py
@@ -113,7 +113,9 @@ def magic_calc(x, y, z):
 def magic(pm, pf):
     """Function docstring"""
     # Adjustments
+    # pylint: disable=no-value-for-parameter
     outputs = pf.a, pf.b = magic_calc(pm, pf)
+    # pylint: enable=no-value-for-parameter
     header = ['a', 'b']
     return DataFrame(data=np.column_stack(outputs), columns=header)
 
@@ -182,6 +184,9 @@ def test_magic_apply_jit_swap():
     assert_frame_equal(xx, exp)
 
 
+# pylint: disable=no-value-for-parameter
+
+
 def test_magic_iterate_jit():
     """Test docstring"""
     pm = Foo()
@@ -293,6 +298,9 @@ def test_function_parameters_optional():
     assert_frame_equal(ans, exp)
 
 
+# pylint: enable=no-value-for-parameter
+
+
 def unjittable_function1(w, x, y, z):
     """Function docstring"""
     a = x + y
diff --git a/taxcalc/utils.py b/taxcalc/utils.py
index b52a38aa0..7464e5238 100644
--- a/taxcalc/utils.py
+++ b/taxcalc/utils.py
@@ -1311,7 +1311,7 @@ def pch_graph_plot(data,
     fig.yaxis.axis_label_text_font_size = '12pt'
     fig.yaxis.axis_label_text_font_style = 'normal'
     fig.yaxis[0].formatter = PrintfTickFormatter(format='%.1f')
-    # return fig  # bokeh 3.4.1 cannot save this figure for some unknown reason
+    return fig
 
 
 def write_graph_file(figure, filename, title):