  We investigate the patching of double and exceptional field theories. In
double field theory the patching conditions imposed on the spacetime after
solving the strong section condition imply that the 3-form field strength $H$
is exact. A similar conclusion can be reached for the form field strengths of
exceptional field theories after some plausive assumptions are made on the
relation between the transition functions of the additional coordinates and the
patching data of the form field strengths. We illustrate the issues that arise,
and explore several alternative options which include the introduction of
C-folds and of the topological geometrisation condition.
