title: Jupyter Notebook: (OperationalError('disk I/O error',))
body: <p>I'm getting the following error on running an existing Jupyter Notebook file </p>
  
  <pre><code>The history saving thread hit an unexpected error (OperationalError('disk I/O error',)).History will not be written to the database.
  </code></pre>
  
  <p>Never the less, the remaining code in the notebook executes properly after that. However, when I'm trying to create a new notebook file this error is not letting me create it and I get the following error:</p>
  
  <pre><code>Error while saving file: python_notebook_ollie/Untitled2.ipynb disk I/O error
  Traceback (most recent call last):
    File "/work/ollie/muali/miniconda3/lib/python3.6/site-packages/notebook/services/contents/filemanager.py", line 421, in save
      self.check_and_sign(nb, path)
    File "/work/ollie/muali/miniconda3/lib/python3.6/site-packages/notebook/services/contents/manager.py", line 440, in check_and_sign
      self.notary.sign(nb)
    File "/work/ollie/muali/miniconda3/lib/python3.6/site-packages/nbformat/sign.py", line 449, in sign
      self.store.store_signature(signature, self.algorithm)
    File "/work/ollie/muali/miniconda3/lib/python3.6/site-packages/nbformat/sign.py", line 207, in store_signature
      if not self.check_signature(digest, algorithm):
    File "/work/ollie/muali/miniconda3/lib/python3.6/site-packages/nbformat/sign.py", line 241, in check_signature
      self.db.commit()
  sqlite3.OperationalError: disk I/O error
  [W 15:08:48.093 NotebookApp] Unexpected error while saving file: python_notebook_ollie/Untitled2.ipynb disk I/O error
  [E 15:08:48.094 NotebookApp] {
    "Host": "localhost:15695",
    "User-Agent": "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0",
    "Accept": "application/json, text/javascript, */*; q=0.01",
    "Accept-Language": "en-US,en;q=0.5",
    "Accept-Encoding": "gzip, deflate",
    "Referer": "http://localhost:15695/notebooks/python_notebook_ollie/Traj_case_study.ipynb",
    "Content-Type": "application/json",
    "X-Xsrftoken": "2|96ae1fed|bde68f8333dd4b46b900b02246747fa4|1520496687",
    "X-Requested-With": "XMLHttpRequest",
    "Content-Length": "19",
    "Cookie": "_xsrf=2|96ae1fed|bde68f8333dd4b46b900b02246747fa4|1520496687; username-localhost-15695=\"2|1:0|10:1520518043|24:username-localhost-15695|44:NjE5MWZlMWIzMjdmNGE2N2FlZmQ3NmE3NzRlNmNiZmQ=|8062f4c541e5dcef0d8b4a2d7e75cc59f1d27197ac4633b9da64b7bb94aae7a4\"",
    "Connection": "keep-alive"
  }  
  </code></pre>
  
  <p>I tried to follow this <a href="https://stackoverflow.com/questions/21352285/ipython-operationalerror-disk-i-o-error">answer</a> and deleted the history.sqlite file but, still I'm getting the disk I/O error. </p>
  
  <p>Some threads on github say NFS based mount can create some problems but in the past it was working fine <em>until I upgraded my matplotlib package.</em> I've now downgraded that package but I still can't get rid of the error.   </p>
  
  <p>Edit: The first error displayed on the terminal while opening an .ipynb file is </p>
  
  <pre><code>The signatures database cannot be opened; maybe it is corrupted or  
  
  encrypted. You may need to rerun your notebooks to ensure that they are trusted to run Javascript. The old signatures database has been renamed to ~/.local/share/jupyter/nbsignatures.db.bak and a new one has been created.
  </code></pre>