Question: I have this script that I attached a GUI to the front of and wanted to distribute it to other DnD DMs for them to use to overlay grids onto images. Only issue is that everytime I try to package the python script using Pyinstaller, it keeps throwing two different errors. If I run pyinstaller --hidden-import matplotlib myscript.py it returns  NameError: name 'defaultParams' is not defined [7532] Failed to execute script ImageGridder  So I decided to try and run the command again with the --onefile option. When I do so it returns,  RuntimeError: Could not find the matplotlib data files [18884] Failed to execute script ImageGridder  Now in both examples, the packaging process completes, and all of the files seem to be generated correctly. It's just when I run the .exe it generates, it crashes. I know the file itself runs properly as I have gotten it to run and work properly on both my desktop and laptop. I've done a good few hours of searching for anything that would help, but nothing really seems to work. The script itself, from PIL import Image import tkinter as tk from tkinter import filedialog import matplotlib.pyplot as PLT import matplotlib.ticker as plticker class gridder(tk.Tk): def __init__(self): tk.Tk.__init__(self) self.initialize() def initialize(self): self.iWidth = tk.StringVar() self.iHeight = tk.StringVar() self.imgSelect = tk.StringVar() self.squareLength= tk.IntVar() self.ratioX=tk.IntVar() self.ratioY=tk.IntVar() self.checkSquare = tk.IntVar() self.colorLine= tk.StringVar() self.colorLine.set('k') self.checkSquare.set(0) self.ratioX.set(10) self.ratioY.set(10) self.squareLength.set(120) # row 1 labelDisclaim = tk.Label(self, text='Currently only works with jpegs') labelDisclaim.grid(column=2, row=1) # row 2 buttonOpen = tk.Button(self, text="Select an Image", command=self.openExplorer) buttonOpen.grid(column=1, row=2) labelSelected= tk.Label(self, text="Selected Image: ") labelSelected.grid(column=2,row=2) labelImgName = tk.Label(self, textvariable=self.imgSelect) labelImgName.grid(column=3,row=2) # row 3 labelStaticImg= tk.Label(self, text="Width of image, in pixels: ") labelStaticImg.grid(column=1,row=3) labelImgWidth = tk.Label(self, textvariable=self.iWidth, anchor='w') labelImgWidth.grid(column=2,row=3) labelStaticHeight= tk.Label(self, text="Height of image, in pixels: ") labelStaticHeight.grid(column=3,row=3) labelImgHeight = tk.Label(self, textvariable=self.iHeight, anchor='w') labelImgHeight.grid(column=4,row=3) # row 4 labelRatioX = tk.Label(self, text="Enter the Ratio along the X axis, default is 10: ") labelRatioX.grid(column=1,row=4) entryRatioX = tk.Entry(self, textvariable=self.ratioX) entryRatioX.grid(column=2,row=4) labelRatioY =tk.Label(self, text="Enter the Ratio along the Y axis, default is 10: ") labelRatioY.grid(column=3,row=4) entryRatioY = tk.Entry(self, textvariable=self.ratioY) entryRatioY.grid(column=4,row=4) # row 5 labelSquare = tk.Label(self, text="For strict squares, in the sense of a battle map, check this ->") labelSquare.grid(column=1,row=5) checkboxSquare = tk.Checkbutton(self, variable=self.checkSquare, text="If checked, it will ignore the ratio and apply squares that are specified by the entry, (default 120x120) ->",wraplength=150) checkboxSquare.grid(column=2,row=5) labelSquareLength = tk.Label(self, text="Side length of Square: ") labelSquareLength.grid(column=3,row=5) entrySquareLength = tk.Entry(self, textvariable=self.squareLength) entrySquareLength.grid(column=4,row=5) # row 6 labelColor= tk.Label(self, text="Enter a color for the grid, valid choices black=k, blue=b, green=g, red=r, white=w, brown=brown, yellow=yellow, cyan=c. Default is black: ",wraplength=250) labelColor.grid(column=1,row=6) entryColor = tk.Entry(self, textvariable=self.colorLine) entryColor.grid(column=2,row=6) execButton = tk.Button(self, text="Gridify", command=self.gridify) execButton.grid(column=4,row=6) # row 9 button = tk.Button(self,text="Exit",command=self.closeProgram) button.grid(column=2,row=9) # row 10 labelSig = tk.Label(self, text='By Johnathan Keith, 2020. Ver 1.0. This is free-to-use, and will always be. This was willingly distributed to the public.',wraplength=350) labelSig.grid(column=2,row=10) labelDisclaimer = tk.Label(self, text="This program does NOT generate pop up windows for bad data entries. If the image does not generate into the folder the script is in, you did something wrong.",wraplength=200) labelDisclaimer.grid(column=4,row=10) def openFile(self, imagefilename): Img = Image.open(imagefilename) height, width = Img.size self.iHeight.set(height) self.iWidth.set(width) def gridify(self): ratioX=0 ratioY=0 sidelengthy=0 sidelengthx=0 if self.checkSquare.get(): ratioX=int(self.squareLength.get()) ratioY=int(self.squareLength.get()) sidelengthx=ratioX sidelengthy=ratioY else: ratioX=int(self.ratioX.get()) ratioY=int(self.ratioY.get()) sidelengthy=int(self.iWidth.get())/ratioY sidelengthx=int(self.iHeight.get())/ratioX image=Image.open(self.imgSelect.get()) my_dpi=300. #set the figure up fig=PLT.figure(figsize=(float(image.size[0])/my_dpi,float(image.size[1])/my_dpi),dpi=my_dpi) ax=fig.add_subplot(111) #remove whitespace fig.subplots_adjust(left=0,right=1,bottom=0,top=1) #set gridding interval locx = plticker.MultipleLocator(base=sidelengthx) locy = plticker.MultipleLocator(base=sidelengthy) ax.xaxis.set_major_locator(locx) ax.yaxis.set_major_locator(locy) #add the grid ax.grid(which='major', axis='both', linestyle='-',color=self.colorLine.get()) ax.imshow(image) token=self.imgSelect.get().split('/') saveName= "gridded_"+token[-1] # Save the figure fig.savefig(saveName,dpi=my_dpi) def closeProgram(self): self.destroy() exit() def dataEntry(self): if type(int) == type(int(bHeight)): self.bHeight = int(entryHeight.get()) else: return def openExplorer(self): filename= filedialog.askopenfilename(initialdir="/", title="Select an Image", filetypes=(("jpeg files", "*.jpg"),("all files", "*.*"))) if filename: self.imgSelect.set(filename) self.openFile(filename) if __name__ == "__main__": app = gridder() app.title('Image Gridder') app.mainloop()  I am running python 3.8, matplotlib 3.3.0, tkinter, and PIL 6.2.2, and pyinstaller 3.6. The contents of the warning file while using the --onefile command:  This file lists modules PyInstaller was not able to find. This does not necessarily mean this module is required for running you program. Python and Python 3rd-party packages include a lot of conditional or optional modules. For example the module 'ntpath' only exists on Windows, whereas the module 'posixpath' only exists on Posix systems. Types if import: * top-level: imported at the top-level - look at these first * conditional: imported within an if-statement * delayed: imported from within a function * optional: imported within a try-except-statement IMPORTANT: Do NOT post this list to the issue-tracker. Use it as a basis for yourself tracking down the missing module. Thanks! missing module named _posixsubprocess - imported by subprocess (optional), multiprocessing.util (delayed) missing module named 'org.python' - imported by copy (optional), xml.sax (delayed, conditional), setuptools.sandbox (conditional) missing module named _frozen_importlib_external - imported by importlib._bootstrap (delayed), importlib (optional), importlib.abc (optional), zipimport (top-level) excluded module named _frozen_importlib - imported by importlib (optional), importlib.abc (optional), zipimport (top-level), PyInstaller.loader.pyimod02_archive (delayed, conditional) missing module named urllib.pathname2url - imported by urllib (conditional), PyInstaller.lib.modulegraph._compat (conditional) missing module named _posixshmem - imported by multiprocessing.resource_tracker (conditional), multiprocessing.shared_memory (conditional) missing module named multiprocessing.set_start_method - imported by multiprocessing (top-level), multiprocessing.spawn (top-level) missing module named multiprocessing.get_start_method - imported by multiprocessing (top-level), multiprocessing.spawn (top-level) missing module named _scproxy - imported by urllib.request (conditional) missing module named termios - imported by tty (top-level), getpass (optional) missing module named resource - imported by posix (top-level), test.support (optional) missing module named 'java.lang' - imported by platform (delayed, optional), xml.sax._exceptions (conditional) missing module named vms_lib - imported by platform (delayed, conditional, optional) missing module named java - imported by platform (delayed) missing module named _winreg - imported by platform (delayed, optional), numpy.distutils.cpuinfo (delayed, conditional, optional), pkg_resources._vendor.appdirs (delayed, conditional) missing module named multiprocessing.get_context - imported by multiprocessing (top-level), multiprocessing.pool (top-level), multiprocessing.managers (top-level), multiprocessing.sharedctypes (top-level) missing module named multiprocessing.TimeoutError - imported by multiprocessing (top-level), multiprocessing.pool (top-level) missing module named multiprocessing.BufferTooShort - imported by multiprocessing (top-level), multiprocessing.connection (top-level) missing module named multiprocessing.AuthenticationError - imported by multiprocessing (top-level), multiprocessing.connection (top-level) missing module named asyncio.DefaultEventLoopPolicy - imported by asyncio (delayed, conditional), asyncio.events (delayed, conditional) missing module named readline - imported by cmd (delayed, conditional, optional), code (delayed, conditional, optional), pdb (delayed, optional) missing module named org - imported by pickle (optional) missing module named grp - imported by shutil (optional), tarfile (optional), pathlib (delayed), distutils.archive_util (optional) missing module named pwd - imported by posixpath (delayed, conditional), shutil (optional), tarfile (optional), pathlib (delayed, conditional, optional), http.server (delayed, optional), webbrowser (delayed), netrc (delayed, conditional), getpass (delayed), distutils.util (delayed, conditional, optional), distutils.archive_util (optional) missing module named posix - imported by os (conditional, optional), shutil (conditional) missing module named 'multiprocessing.forking' - imported by C:\Users\Owner\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\PyInstaller\loader\rthooks\pyi_rth_multiprocessing.py (optional) missing module named 'win32com.gen_py' - imported by win32com (conditional, optional), C:\Users\Owner\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\PyInstaller\loader\rthooks\pyi_rth_win32comgenpy.py (top-level) missing module named pyimod03_importers - imported by PyInstaller.loader.pyimod02_archive (delayed, conditional), C:\Users\Owner\AppData\Local\Programs\Python\Python38-32\Lib\site-packages\PyInstaller\loader\rthooks\pyi_rth_pkgres.py (top-level) missing module named 'pkg_resources.extern.pyparsing' - imported by pkg_resources._vendor.packaging.requirements (top-level), pkg_resources._vendor.packaging.markers (top-level) missing module named _uuid - imported by uuid (optional) missing module named __builtin__ - imported by PIL.Image (optional), numpy.core.numerictypes (conditional), numpy.core.numeric (conditional), numpy.lib.function_base (conditional), numpy.lib._iotools (conditional), numpy.ma.core (conditional), numpy.distutils.misc_util (delayed, conditional), numpy (conditional), pyparsing (conditional), pkg_resources._vendor.pyparsing (conditional), setuptools._vendor.pyparsing (conditional) missing module named ordereddict - imported by pyparsing (optional), pkg_resources._vendor.pyparsing (optional), setuptools._vendor.pyparsing (optional) missing module named StringIO - imported by PyInstaller.lib.modulegraph._compat (conditional), PyInstaller.lib.modulegraph.zipio (conditional), setuptools._vendor.six (conditional), numpy.lib.utils (delayed, conditional), numpy.lib.format (delayed, conditional), numpy.testing._private.utils (conditional), six (conditional), pkg_resources._vendor.six (conditional) missing module named 'com.sun' - imported by pkg_resources._vendor.appdirs (delayed, conditional, optional) missing module named com - imported by pkg_resources._vendor.appdirs (delayed) missing module named pkg_resources.extern.packaging - imported by pkg_resources.extern (top-level), pkg_resources (top-level) missing module named pkg_resources.extern.appdirs - imported by pkg_resources.extern (top-level), pkg_resources (top-level) missing module named 'pkg_resources.extern.six.moves' - imported by pkg_resources (top-level), pkg_resources._vendor.packaging.requirements (top-level) missing module named pkg_resources.extern.six - imported by pkg_resources.extern (top-level), pkg_resources (top-level), pkg_resources.py31compat (top-level) missing module named pytest - imported by numpy._pytesttester (delayed), matplotlib (delayed, optional) missing module named commands - imported by numpy.distutils.cpuinfo (conditional) missing module named setuptools.extern.packaging - imported by setuptools.extern (top-level), setuptools.dist (top-level), setuptools.command.egg_info (top-level) missing module named 'setuptools.extern.six' - imported by setuptools (top-level), setuptools.extension (top-level) missing module named 'setuptools.extern.packaging.version' - imported by setuptools.config (top-level), setuptools.msvc (top-level) missing module named setuptools.extern.six.moves.filterfalse - imported by setuptools.extern.six.moves (top-level), setuptools.dist (top-level), setuptools.msvc (top-level) missing module named setuptools.extern.six.moves.filter - imported by setuptools.extern.six.moves (top-level), setuptools.dist (top-level), setuptools.ssl_support (top-level), setuptools.command.py36compat (top-level) missing module named _manylinux - imported by setuptools.pep425tags (delayed, optional) missing module named 'setuptools.extern.packaging.utils' - imported by setuptools.wheel (top-level) missing module named wincertstore - imported by setuptools.ssl_support (delayed, optional) missing module named 'backports.ssl_match_hostname' - imported by setuptools.ssl_support (optional) missing module named backports - imported by setuptools.ssl_support (optional) missing module named 'setuptools._vendor.six.moves' - imported by 'setuptools._vendor.six.moves' (top-level) missing module named 'setuptools.extern.pyparsing' - imported by setuptools._vendor.packaging.markers (top-level), setuptools._vendor.packaging.requirements (top-level) missing module named setuptools.extern.six.moves.map - imported by setuptools.extern.six.moves (top-level), setuptools.dist (top-level), setuptools.command.easy_install (top-level), setuptools.sandbox (top-level), setuptools.package_index (top-level), setuptools.ssl_support (top-level), setuptools.command.egg_info (top-level), setuptools.namespaces (top-level) runtime module named setuptools.extern.six.moves - imported by setuptools.dist (top-level), setuptools.py33compat (top-level), configparser (top-level), setuptools.command.easy_install (top-level), setuptools.sandbox (top-level), setuptools.command.setopt (top-level), setuptools.package_index (top-level), setuptools.ssl_support (top-level), setuptools.command.egg_info (top-level), setuptools.command.py36compat (top-level), setuptools.namespaces (top-level), setuptools.msvc (top-level), 'setuptools._vendor.six.moves' (top-level) missing module named setuptools.extern.six - imported by setuptools.extern (top-level), setuptools.monkey (top-level), setuptools.dist (top-level), setuptools.extern.six.moves (top-level), setuptools.py33compat (top-level), setuptools.config (top-level), setuptools.command.easy_install (top-level), setuptools.sandbox (top-level), setuptools.py27compat (top-level), setuptools.package_index (top-level), setuptools.wheel (top-level), setuptools.pep425tags (top-level), setuptools.command.egg_info (top-level), setuptools.command.sdist (top-level), setuptools.command.bdist_egg (top-level), setuptools.unicode_utils (top-level), setuptools.command.develop (top-level) missing module named 'numpy_distutils.cpuinfo' - imported by numpy.f2py.diagnose (delayed, conditional, optional) missing module named 'numpy_distutils.fcompiler' - imported by numpy.f2py.diagnose (delayed, conditional, optional) missing module named 'numpy_distutils.command' - imported by numpy.f2py.diagnose (delayed, conditional, optional) missing module named numpy_distutils - imported by numpy.f2py.diagnose (delayed, optional) missing module named __svn_version__ - imported by numpy.f2py.__version__ (optional) missing module named numarray - imported by numpy.distutils.system_info (delayed, conditional, optional) missing module named Numeric - imported by numpy.distutils.system_info (delayed, conditional, optional) missing module named ConfigParser - imported by numpy.distutils.system_info (conditional), numpy.distutils.npy_pkg_config (conditional) missing module named _curses - imported by curses (top-level), curses.has_key (top-level) missing module named _dummy_threading - imported by dummy_threading (optional) missing module named 'nose.plugins' - imported by numpy.testing._private.noseclasses (top-level), numpy.testing._private.nosetester (delayed) missing module named scipy - imported by numpy.testing._private.nosetester (delayed, conditional) missing module named 'nose.util' - imported by numpy.testing._private.noseclasses (top-level) missing module named nose - imported by numpy.testing._private.utils (delayed, optional), numpy.testing._private.decorators (delayed), numpy.testing._private.noseclasses (top-level) missing module named dummy_thread - imported by numpy.core.arrayprint (conditional, optional) missing module named thread - imported by numpy.core.arrayprint (conditional, optional), PyInstaller.loader.pyimod02_archive (conditional) missing module named cPickle - imported by numpy.core.numeric (conditional) missing module named cStringIO - imported by cPickle (top-level) missing module named copy_reg - imported by cPickle (top-level), cStringIO (top-level), numpy.core (conditional) missing module named pickle5 - imported by numpy.core.numeric (conditional, optional) missing module named numpy.core.number - imported by numpy.core (delayed), numpy.testing._private.utils (delayed) missing module named numpy.core.signbit - imported by numpy.core (delayed), numpy.testing._private.utils (delayed) missing module named numpy.core.float64 - imported by numpy.core (delayed), numpy.testing._private.utils (delayed) missing module named numpy.core.float32 - imported by numpy.core (top-level), numpy.testing._private.utils (top-level) missing module named numpy.lib.i0 - imported by numpy.lib (top-level), numpy.dual (top-level) missing module named numpy.core.integer - imported by numpy.core (top-level), numpy.fft.helper (top-level) missing module named numpy.core.sqrt - imported by numpy.core (top-level), numpy.linalg.linalg (top-level), numpy.fft.fftpack (top-level) missing module named numpy.core.conjugate - imported by numpy.core (top-level), numpy.fft.fftpack (top-level) missing module named numpy.core.divide - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.object_ - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.intp - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.geterrobj - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.add - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.complexfloating - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.inexact - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.cdouble - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.csingle - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.double - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named numpy.core.single - imported by numpy.core (top-level), numpy.linalg.linalg (top-level) missing module named future_builtins - imported by numpy.lib.npyio (conditional) missing module named urllib2 - imported by numpy.lib._datasource (delayed, conditional) missing module named urlparse - imported by numpy.lib._datasource (delayed, conditional) missing module named numpy.recarray - imported by numpy (top-level), numpy.ma.mrecords (top-level) missing module named numpy.dtype - imported by numpy (top-level), numpy.ma.mrecords (top-level), numpy.ctypeslib (top-level) missing module named numpy.expand_dims - imported by numpy (top-level), numpy.ma.core (top-level) missing module named numpy.array - imported by numpy (top-level), numpy.ma.core (top-level), numpy.ma.extras (top-level), numpy.ma.mrecords (top-level), numpy.ctypeslib (top-level) missing module named numpy.bool_ - imported by numpy (top-level), numpy.ma.core (top-level), numpy.ma.mrecords (top-level) missing module named numpy.iscomplexobj - imported by numpy (top-level), numpy.ma.core (top-level) missing module named numpy.amin - imported by numpy (top-level), numpy.ma.core (top-level) missing module named numpy.amax - imported by numpy (top-level), numpy.ma.core (top-level) missing module named numpy.ndarray - imported by numpy (top-level), numpy.ma.core (top-level), numpy.ma.extras (top-level), numpy.ma.mrecords (top-level), numpy.ctypeslib (top-level) missing module named numpy.histogramdd - imported by numpy (delayed), numpy.lib.twodim_base (delayed) missing module named numpy.eye - imported by numpy (delayed), numpy.core.numeric (delayed) missing module named six.moves.zip - imported by six.moves (top-level), cycler (top-level) runtime module named six.moves - imported by cycler (top-level), dateutil.tz.tz (top-level), dateutil.tz._factories (top-level), dateutil.tz.win (top-level), dateutil.rrule (top-level) missing module named six.moves.range - imported by six.moves (top-level), dateutil.rrule (top-level) missing module named colorama - imported by tornado.log (optional) missing module named typing_extensions - imported by tornado.ioloop (conditional), tornado.websocket (conditional) missing module named fcntl - imported by tornado.platform.posix (top-level) missing module named dateutil.tz.tzfile - imported by dateutil.tz (top-level), dateutil.zoneinfo (top-level) missing module named shiboken - imported by matplotlib.backends.qt_compat (delayed, conditional) missing module named PySide - imported by matplotlib.backends.qt_compat (delayed, conditional) missing module named PyQt4 - imported by matplotlib.backends.qt_compat (delayed) missing module named shiboken2 - imported by matplotlib.backends.qt_compat (delayed, conditional) missing module named PySide2 - imported by PIL.ImageQt (conditional, optional), matplotlib.backends.qt_compat (delayed, conditional) missing module named sip - imported by matplotlib.backends.qt_compat (delayed, conditional, optional), PyQt5 (top-level) missing module named matplotlib.axes.Axes - imported by matplotlib.axes (top-level), matplotlib.pyplot (top-level), matplotlib.legend (delayed), matplotlib.projections.geo (top-level), matplotlib.projections.polar (top-level), mpl_toolkits.mplot3d.axes3d (top-level), matplotlib.figure (top-level) missing module named 'IPython.core' - imported by matplotlib.backend_bases (delayed), matplotlib.pyplot (delayed, conditional, optional) missing module named IPython - imported by matplotlib.backend_bases (delayed), matplotlib.pyplot (delayed, conditional, optional) missing module named matplotlib.tri.Triangulation - imported by matplotlib.tri (top-level), matplotlib.tri.trifinder (top-level), matplotlib.tri.tritools (top-level), matplotlib.tri.triinterpolate (top-level) missing module named matplotlib.axes.Subplot - imported by matplotlib.axes (top-level), matplotlib.pyplot (top-level) missing module named olefile - imported by PIL.MicImagePlugin (top-level), PIL.FpxImagePlugin (top-level) missing module named UserDict - imported by PIL.PdfParser (optional) missing module named Tkinter - imported by PIL.ImageTk (conditional) missing module named 'PySide.QtCore' - imported by PIL.ImageQt (conditional, optional) missing module named 'PyQt4.QtCore' - imported by PIL.ImageQt (conditional, optional) missing module named 'PySide2.QtCore' - imported by PIL.ImageQt (conditional, optional) missing module named pathlib2 - imported by PIL.Image (optional) missing module named cffi - imported by PIL.Image (optional), PIL.PyAccess (top-level), win32ctypes.core (optional), PIL.ImageTk (delayed, conditional, optional) 

Answer: You can try to solve this problem by installing older versions of the matplotlib package. eg: pip install matplotlib==3.2.2