ipython: DatabaseError: database disk image is malformed

After shutdown (ctrl+c) and restart of ipython notebook I get this error:

[E 17:26:06.417 NotebookApp] Unhandled error in API request
    Traceback (most recent call last):
      File "/home/ml/anaconda2/lib/python2.7/site-packages/notebook/base/handlers.py", line 458, in wrapper
        result = yield gen.maybe_future(method(self, *args, **kwargs))
      File "/home/ml/anaconda2/lib/python2.7/site-packages/tornado/gen.py", line 1008, in run
        value = future.result()
      File "/home/ml/anaconda2/lib/python2.7/site-packages/tornado/concurrent.py", line 232, in result
        raise_exc_info(self._exc_info)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/tornado/gen.py", line 282, in wrapper
        yielded = next(result)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/notebook/services/contents/handlers.py", line 124, in get
        path=path, type=type, format=format, content=content,
      File "/home/ml/anaconda2/lib/python2.7/site-packages/notebook/services/contents/filemanager.py", line 354, in get
        model = self._notebook_model(path, content=content)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/notebook/services/contents/filemanager.py", line 314, in _notebook_model
        self.mark_trusted_cells(nb, path)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/notebook/services/contents/manager.py", line 447, in mark_trusted_cells
        trusted = self.notary.check_signature(nb)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/nbformat/sign.py", line 220, in check_signature
        if self.db is None:
      File "/home/ml/anaconda2/lib/python2.7/site-packages/traitlets/traitlets.py", line 529, in __get__
        return self.get(obj, cls)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/traitlets/traitlets.py", line 508, in get
        value = self._validate(obj, dynamic_default())
      File "/home/ml/anaconda2/lib/python2.7/site-packages/nbformat/sign.py", line 127, in _db_default
        self.init_db(db)
      File "/home/ml/anaconda2/lib/python2.7/site-packages/nbformat/sign.py", line 139, in init_db
        )""")
    DatabaseError: database disk image is malformed

The following similar issues did not help in solving: https://github.com/ipython/ipython/issues/2097 https://github.com/ipython/ipython/issues/7795 https://github.com/ipython/ipython/issues/8294 https://github.com/ipython/ipython/issues/8997