I saw old questions here why the SD errors on our phone saying SD card unmounting, and preparing for SD card, since the post is open still, here it goes for me. Been searching reading all over the webs, and asking cell phone company's why this is a problem for most all of us? my wife has a S4 her phone with a 64gb Patriot only failed once, got corrupted, put a new one in, no problems for 2 years and she never got the unmounted errors.
Now me, I have the S5 for a little over a 1/1/2 year, always with a Patriot 64gb card, yes I have had the corrupt message too, but had no unmounted errors happen. But now since 2 months been having the unmounted errors ever since. I formated it, worked for a few days, back again with errors. Then put a new in one again, formated it still no go.
Been told by Verizon that Sandisk, and Patriots are the worsted cards, form what he heard.
Now for the GOOD news for me, I told the Verizon guy that I have a Gigastone GS-2in1x1064G-R Class 10 UHS-1 microSDHC with adapter they range from $16.00 up to 25.00 in my S5 for 4 days, even forced the raise the temp. up on it too 101 degrees. YAHOO! so far OK.
I had one more extra Patriot one not used or opend it, and returned it to Costco. Going to Frys and get me another Gigastone, and they will have to match the price from Amazon. $15.61 WOW! Good luck for everyone.
Now for a update: It's been about 5-6 days now, I bought a 64GB for a spare and a 128GB both the Gigastone at Frys, they had to price match them, the 128 27.99, and 15.51. The 128GB in my phone has been holding up with no errors. Fast little guy for 128GB.