More troubleshooting tips

Author: Dean Wampler

reference/Troubleshooting-Tips-Tricks.ipynb

@@ -115,6 +115,41 @@
     "They are related to the graphing libraries we use and appear to be harmless."
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### \"ImportError: No module named gym\"\n",
+    "\n",
+    "If you are working on a laptop and using Anaconda, and you get import errors for modules like `gym`, e.g., _ImportError: No module named gym_, this probably indicates you have the wrong `python` and `pip` commands on your path ahead of the versions for your Conda environment. To verify, use the `which` command:\n",
+    "\n",
+    "```shell\n",
+    "$ which -a python\n",
+    "/usr/bin/python\n",
+    "/Users/me/anaconda3/envs/anyscale-academy/bin/python\n",
+    "```\n",
+    "\n",
+    "In this example, the built-in `python` is ahead of the correct Conda environment `python`.\n",
+    "\n",
+    "To fix, try the following:\n",
+    "\n",
+    "First, try activiting the `anyscale-academy` environment again: \n",
+    "\n",
+    "```shell\n",
+    "conda activate anyscale-academy\n",
+    "```\n",
+    "\n",
+    "(see the [README](../README.md) for more details about the Conda environment we are using).\n",
+    "\n",
+    "Run `which -a python` again. Does it show your `~/anaconda3/envs/anyscale-academy/bin/python` first? If not, force the correct ordering by changing the path: \n",
+    "\n",
+    "```shell\n",
+    "export PATH=$HOME/anaconda3/envs/anyscale-academy/bin:$PATH\n",
+    "```\n",
+    "\n",
+    "Run the `which` command again to confirm the correct `python` is now first in the list."
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},