Hello Sunidhi Bhatt

just update your python3 version and try to run

here I shared the sudo installation commands for updating

python3 --version

sudo apt-get update

sudo apt-get install python3.6

sudo apt-get -y install python3-pip

pip3 install networkx == 2.3

Thank you so much @Premkumar Krish

"cgenff_charmm2gmx.py" requires Python 3.0 or higher, but you are using a Python version in the 2.x series. To resolve this issue, you need to make sure that you are running the script with a compatible Python version.

To resolve the problem:

1. Check Python version: Confirm the version of Python installed on your system. Open a terminal or command prompt and type `python --version` or `python3 --version` to check the installed Python version. If you see a version in the 2.x series, you will need to install Python 3.x.

2. Install Python 3.x: If you don't have Python 3.x installed, you can download and install it from the official Python website (https://www.python.org/). Make sure to choose the appropriate version for your operating system.

3. Verify Python 3 installation: After installing Python 3.x, verify that it is correctly installed by running `python3 --version` in the terminal or command prompt. This should display the installed Python 3 version.

4. Run the script with Python 3: Once Python 3.x is installed, use the `python3` command instead of `python` to run the script. For example, in your case, you would run the following command:

````

python3 cgenff_charmm2gmx.py UNK unk_fix.mol2 unk.str charmm36-jul2022.ff

```

Hope it helps

I tried this approach as well but unable to fix the issue yet