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Users of the current PS1 DR2 data should be aware of a few issues and inconsistencies in the data.

• Approximately 4.9 square degrees (0.016% of the survey area) has sources that are missing due to various issues in the database population procedures.  These are expected to be filled in during the coming monthseventually.
• The stack positions (raStack, decStack) have considerably larger systematic astrometric errors than the mean epoch positions (raMean, decMean).
• The astrometric and photometric keywords in the image headers are slightly inconsistent with the astrometry and photometry for catalog objects. The catalog quantities are more accurate due to post-image-processing improvements.
• Some images near the celestial pole have registration issues that lead to poor photometry and astrometry.
• There are some astrometry issues at the ~0.5" level near the pole (mostly above 85 deg declination) which have caused problems with the stacking. As a result, both warp and stack images may have incorrect WCS, and in extreme cases double objects may be visible in the stacks. There will also be errors in the stack positions (but not mean epoch positions) in the catalogues.
• FITS image headers use the obsolete PC001001, PC001002, etc., keywords for the WCS. The fluxes have been non-linearly scaled using an asinh transformation. The files also use the tile-compressed image format.  The full skycell FITS images do not have a RADESYS keyword, which leads some software (including DS9 v8) to incorrectly interpret the coordinates as being equinox 1950 rather than equinox 2000.  The fix is to insert the keyword RADESYS = 'FK5' in the header. The headers also lack the TIMESYS = 'TAI' keyword, which is important if you care about the image observation dates at an accuracy of 30 seconds.