'We know slot 1 is physically different inside. I purchased them from Amazon UK at the end of Aug 2019. The batch number printed on the back of both of my 256GB SanDisk Extreme PRO cards (SDXC 170MB/s V30 U3 Class10 I) is 13 characters ending with 52123G It does not work in slot 1 and does not properly format the card in slot 1 It lets me take photos, and it lets me (re)format the card I've now found that the 256GB card does actually work if I put it in slot 2 and select 'slot 2' from the menuįound in Setup6 > Rec. I am running v3.01 which should be the latest firmware so there is nothing for me to upgrade (my A7iii camera came with this firmware number) YouTube: Sandisk card issue with Sony a7iii & a7riii Maybe this is a similar thing happening over again with the Extreme PRO 256GB cards? Sony issued a firmware update (v2.1) that seemed to fix everyone's problems. A7iii) and SanDisk Extreme PRO memory cards (but with most people mentioning the 64/128GB ones a year or two back, possibly a batch code ending 151766G). There have been widespread problems with the Sony Alpha cameras (eg. Further research has led me down an interesting rabbit-hole.

How to format sd card on sony a7iii