HSA contributions tells me to enter info in box 12 on w2, but there are 4 different box 12. i entered box 12c-W, but then im redirected to fix it during review.

[DaveF1006]

It depends.  To clarify, did you make 4 different entries in Box 12, all with different codes?

[Opus 17]

There are more than 20 different tax items that might be listed in box 12, each has its own letter code.  Most W-2s seem to allow 4 items in box 12 (sometimes called 12a, 12b, etc.).  But "12b" is not the code.  The code is one or 2 capital letters.  For example, code "D" is contributions to a 401(k) plan, and code "AA" is contributions to a designated Roth account at a 401(k).  

HSA contributions have code "W".

You should enter all the items from your W-2, if you have more than one box 12 item, enter them all with their correct letter code.