Express won't update maps in Nuvi 2557LMT

See https://support.garmin.com/en-US/?faq=GuclsqmdI02dC0ULxHR2T6

If that doesn't help you then call Product Support as you will have a problem somewhere, most users update with no issue. Details for Product Support are given at the bottom of the FAQ

At the link SUSSAMB provided item #2 is "Ensure Your Computer Has Enough Free Disk Space" but with little guidance with respect to that action.  One big "hog" on space is old maps that Garmin Express fails to remove after a map update.  These maps are in the folder C:\ProgramData\Garmin\CoreService\Downloads\Map and named something like Map_Map.NA2021.20 or similar. Each folder is 6+ GB.  If you have several, delete the oldest, leaving behind the last one or two.  Then make sure you empty the recycle bin and test the updates.

If per chance you can't find the referenced folder, it is sometimes "hidden" in a Windows installation.  The process to "unhide" items is basically select the Start button, then select Control Panel > Appearance and Personalization. Select Folder Options, then select the View tab. Under Advanced settings, select Show hidden files, folders, and drives, and then select OK.

only one map in folder, thanks anyway

Product support suggested I use another computer. Tried an old Win 7 Netbook. Couldn't even add the device to Express--no "NEXT" button on the add page. Gave up

Do you otherwise have plenty of free space?  No less than about 30%, preferably more.

150gb free on 250gb Solid State c drive, 250gb free on 350gb d drive , e and f drives are empty