Sometimes issues can occur with newly applied paint and cracks can appear on the surface.
This cracking effect can be caused when a brittle paint, such as a standard matt emulsion, is applied over the top of a highly flexible coating such as silk or mid sheen. It can also occur when paint is applied over PVA or wallpaper paste.
As a rule, always avoid the use of PVA as a primer/sealer. Where a sheen finish or PVA is present, use an Alkali Resisting Sealer to prime the surface before repainting with your chosen coating.
In severe instances, lining paper can be applied as an additional layer of protection.