{"id":1618,"date":"2022-08-04T14:43:17","date_gmt":"2022-08-04T14:43:17","guid":{"rendered":"https:\/\/www.pyxll.com\/blog\/?p=1618"},"modified":"2025-09-18T14:01:43","modified_gmt":"2025-09-18T14:01:43","slug":"debug-python-code-in-excel-with-pycharm","status":"publish","type":"post","link":"https:\/\/www.pyxll.com\/blog\/debug-python-code-in-excel-with-pycharm\/","title":{"rendered":"Debug Python in Excel with PyCharm"},"content":{"rendered":"\n

What is PyCharm?<\/h2>\n\n\n\n

PyCharm is an extremely popular Python IDE by JetBrains. Among it’s many features is its excellent visual debugger. The debugger lets you step through Python code, line by line, and inspect variables. We can use this to debug our Python code running in Excel.<\/p>\n\n\n\n

For professional developers getting a development environment set up that works for you is essential. There’s no one right choice, but PyCharm offers a lot that can help increase productivity when writing Python code.<\/p>\n\n\n\n

When writing Python in Excel using PyXLL, you may find at times that you want to use a debugger. Stepping through your code can help you identify what’s going on. A good debugger can be a life saver, and much easier to work with than countless print statements!<\/p>\n\n\n\n

PyCharm works well with PyXLL. It’s debugger can attach to the running Excel process, allowing you to step through your Python code in Excel, line by line. It works just in the same way as you can use PyCharm to step through a Python script!<\/p>\n\n\n\n

At the time of writing you will require the professional (paid) version for the “Attach to Process” feature. This is required to attach the PyCharm debugger to PyXLL and debug Python in Excel.<\/p>\n\n\n\n

Debugging Python in Excel with PyCharm<\/h2>\n\n\n\n

PyCharm\u2019s debugger has an \u201cAttach To Process\u201d feature. That means you can attach the debugger to a running Python process, even one not started by PyCharm. This is perfect for attaching to the Python interpreter running in Excel through PyXLL!<\/p>\n\n\n\n

WARNING<\/strong>:

PyCharm does not yet properly support debugging of Python 3.10<\/strong>.

https:\/\/youtrack.jetbrains.com\/issue\/PY-48037\/Support-attach-to-process-on-Windows-with-Python-310<\/a>

If you are using Python 3.10 until this is resovled by JetBrains you will need to use the old-style “Remote Debugger” documented in the second half of this post.<\/p>\n\n\n\n

Python Debugger Configuration<\/h3>\n\n\n\n

By default, you will only see processes called \u201cpython\u201d when attaching to a process in PyCharm. Before you can attach to Excel to debug your PyXLL functions you need to change. Go to File -> Settings, and under the \u201cBuild, Execution, Deployment\u201d section find the \u201cPython Debugger\u201d settings. Here you will see the setting \u201cFor Attach To Process show processes with names containing:\u201d. This setting is configured as \u201cpython\u201d by default. Change this to \u201cexcel\u201d to show only Excel processes, or leave it blank to show all processes.<\/p>\n\n\n\n

\"\"<\/a>
Python Debugger Settings: Attach to Excel<\/figcaption><\/figure>\n\n\n\n

Attaching to Python in Excel<\/h3>\n\n\n\n

With Excel runinng and the PyXLL add-in loaded, in PyCharm go to \u201cRun -> Attach to Process\u2026\u201d.<\/p>\n\n\n\n

\"\"<\/a>
PyCharm: Attach to Process\u2026<\/figcaption><\/figure>\n\n\n\n

Next PyCharm will present you with a list of processes to choose from. If you followed the steps above to filter the processes containing \u201cexcel\u201d you will only see a single process. That is the Excel process you want to debug.<\/p>\n\n\n\n

\"\"<\/a>
Choose the Excel process to attach to<\/figcaption><\/figure>\n\n\n\n

Choosing the right process<\/h3>\n\n\n\n

If there are multiple Excel processes running check which process you want to attach to using the Windows Task Manager. If you are not sure which process to choose then a quick PyXLL function can tell you the process id. For example:<\/p>\n\n\n

\nfrom pyxll import xl_func\nimport os \n\n@xl_func\ndef getpid():\n    # This will return the Excel process ID so you know which\n    # process to attach the debugger to\n    return os.getpid()\n<\/pre><\/div>\n\n\n
Breakpoints and stepping through the code<\/h3>\n\n\n\n
After you\u2019ve selected the Excel process, PyCharm will start connecting. Once connected you will see the following in the debug console in PyCharm:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
With the debugger connected you can now set breakpoints. When you run your functions in Excel it will stop on those breakpoints, allowing you to step through your code in the usual way.<\/p>\n\n\n\n
Common Problems Attaching to Excel<\/h3>\n\n\n\n
If you have any trouble in attaching the debugger (or if PyCharm shows a timeout error when attempting to connect) check the following:<\/p>\n\n\n\n
    \n
  1. You do not have any of the packages “pydevd_pycharm”, “pydevd”, “debugpy”, or “ptvsd” installed. These will interfer with the operation of PyCharm\u2019s Attach To Process feature unless they are exactly the right version; it is better to not have them installed at all and to let PyCharm use it\u2019s own version of pydevd.

    To uninstall these packages run:
    pip uninstall pydevd_pycharm pydevd debugpy ptvsd<\/code>

    Check they have been removed by looking in your \u201csite-packages\u201d folder.
    \u00a0<\/li>\n\n\n\n
  2. You are using the latest version of PyCharm. PyCharm 2022.2 (Professional Edition) was used while writing this post.
    \u00a0<\/li>\n\n\n\n
  3. Look in your PyXLL log file for any errors.<\/li>\n<\/ol>\n\n\n\n
    For more information about attaching to a process see the PyCharm docs:
    https:\/\/www.jetbrains.com\/help\/pycharm\/attaching-to-local-process.html<\/a><\/p>\n\n\n\n
    Another (older) way to attach PyCharm to Excel<\/h2>\n\n\n\n
    Prior to PyCharm’s “Attach to Process” feature there was another way to attach PyCharm to Excel. PyCharm is also capable to attaching to a remote processs<\/em>, even one running on another computer. You can use this to attach to Excel running locally as well, though it takes a little more work than the method described above.<\/p>\n\n\n\n
    This method is no longer the recommend method. It is left here for anyone unable to upgrade to a newer version of PyCharm.<\/strong><\/p>\n\n\n\n
    The method of debugging Excel using PyCharm’s “Remote Debug” feature is explained in this video:<\/p>\n\n\n\n
    \n