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- Known Issues

# Known Issues

While most bugs and issues are managed using the astropy issue tracker, this document lists issues that are too difficult to fix, may require some intervention from the user to workaround, or are due to bugs in other projects or packages.

## Some docstrings can not be displayed in IPython < 0.13.2

Displaying long docstrings that contain Unicode characters may fail on some platforms in the IPython console (prior to IPython version 0.13.2):

    In [1]: import astropy.units as u

    In [2]: u.Angstrom?
    ERROR: UnicodeEncodeError: 'ascii' codec can't encode character u'\xe5' in
    position 184: ordinal not in range(128) [IPython.core.page]

This can be worked around by changing the default encoding to `utf-8` by adding the following to your `sitecustomize.py` file:

    import sys
    sys.setdefaultencoding('utf-8')

Note that in general, this is not recommended, because it can hide other Unicode encoding bugs in your application. However, in general if your application does not deal with text processing and you just want docstrings to work, this may be acceptable.

The IPython issue: https://github.com/ipython/ipython/pull/2738

## Floating point precision issues on Python 2.6 on Microsoft Windows

When converting floating point numbers to strings on Python 2.6 on a Microsoft Windows platform, some of the requested precision may be lost.

The easiest workaround is to install Python 2.7.

The Python issue: http://bugs.python.org/issue7117

## Failing logging tests when running the tests in IPython

When running the Astropy tests using `astropy.test()` in an IPython interpreter some of the tests in the `astropy/tests/test_logger.py` fail. This is due to mutually incompatible behaviors in IPython and py.test, and is not due to a problem with the test itself or the feature being tested.

See: https://github.com/astropy/astropy/issues/717

## mmap support for `astropy.io.fits` on GNU Hurd

On Hurd and possibly other platforms `flush()` on memory-mapped files is not implemented, so writing changes to a mmap’d FITS file may not be reliable and is thus disabled. Attempting to open a FITS file in writeable mode with mmap will result in a warning (and mmap will be disabled on the file automatically).

See: https://github.com/astropy/astropy/issues/968

## Crash on upgrading from Astropy 0.2 to a newer version

It is possible for installation of a new version of Astropy, or upgrading of an existing installation to crash due to not having permissions on the `~/.astropy/` directory (in your home directory) or some file or subdirectory in that directory. In particular this can occur if you installed Astropy as the root user (such as with `sudo`) at any point. This can manifest in several ways, but the most common is a traceback ending with `ImportError: cannot import name config`. To resolve this issue either run `sudo chown -R <your_username> ~/.astropy` or, if you don’t need anything in it you can blow it away with `sudo rm -rf ~/.astropy`.

See for example: https://github.com/astropy/astropy/issues/987

## Color printing on Windows

Colored printing of log messages and other colored text does work in Windows but only when running in the IPython console. Colors are not currently supported in the basic Python command-line interpreter on Windows.

## Table sorting can silently fail on MacOS X or Windows with Python 3 and Numpy < 1.6.2

In Python 3, prior to Numpy 1.6.2, there was a bug (in Numpy) that caused sorting of structured arrays to silently fail under certain circumstances (for example if the Table contains string columns) on MacOS X, Windows, and possibly other platforms other than Linux. Since `Table.sort` relies on Numpy to internally sort the data, it is also affected by this bug. If you are using Python 3, and need the sorting functionality for tables, we recommend updating to a more recent version of Numpy.

## Anaconda users should upgrade with `conda`, not `pip`

Upgrading Astropy in the anaconda python distribution using `pip` can result in a corrupted install with a mix of files from the old version and the new version. Anaconda users should update with `conda update astropy`. There may be a brief delay between the release of Astropy on PyPI and its release via the `conda` package manager; users can check the availability of new versions with `conda search astropy`.