The biggest headache for any recorder user is the dreaded "Card Error" or slow write speeds. This firmware refines the H1n’s memory controller to better handle modern SDHC cards (Class 10 and UHS-I). If you’ve bought a new 32GB SanDisk or Samsung card recently and experienced freezing or slow start-up, this update should fix that.
: No major bugs or regressions have been widely reported for v1.21, though some users troubleshooting date/time reset issues have experimented with "downgrading" to v1.19 to see if it resolves their specific power-drain preferences. Context from Previous Stable Versions (v1.19) zoom h1n firmware 121