# 16. Custom exceptions and warnings — MDAnalysis.exceptions¶

exception MDAnalysis.exceptions.ApplicationError[source]

Raised when an external application failed.

The error code is specific for the application.

New in version 0.7.7.

exception MDAnalysis.exceptions.ConversionWarning[source]

Warning indicating a problem with converting between units.

exception MDAnalysis.exceptions.DuplicateWarning[source]

Warning indicating possible problems arising from an AtomGroup / ResidueGroup / SegmentGroup containing duplicate Atoms / Residues / Segments.

New in version 0.19.0.

exception MDAnalysis.exceptions.FileFormatWarning[source]

Warning indicating possible problems with a file format.

exception MDAnalysis.exceptions.MissingDataWarning[source]

Warning indicating is that required data are missing.

exception MDAnalysis.exceptions.NoDataError[source]

Raised when empty input is not allowed or required data are missing.

Changed in version 1.0.0: Now a subclass of AttributeError as well as ValueError

exception MDAnalysis.exceptions.SelectionError[source]

Raised when a atom selection failed.

exception MDAnalysis.exceptions.SelectionWarning[source]

Warning indicating a possible problem with a selection.

exception MDAnalysis.exceptions.StreamWarning[source]

Warning indicating a possible problem with a stream.

StreamWarning is used when streams are substituted for simple access by filename (see in particular NamedStream). This does not work everywhere in MDAnalysis (yet).