【Urgent】SD card become read only under android

Urgent!!!
I don't know if this is a bug or not. I used to copy files by selecting the disk drive mode. After that I will safely remove the device under windows before disconnecting the usb cable.

The problem is sometimes after copying files to sdcard, the SD card will become read only under android. For example I cannot copy or create files using file explorer. When using camera app it says "Unable to save file to SD card due to insufficient file permissions". When using album it says "SD card unmounted or not present".

After the problem occurs I cannot access the SD card via disk drive mode anymore, unless I physically removed and reinsert back the SD card.

The strange thing is I can still access the SD card in PC via card reader with no problem. I can also view the existing files in the SD card under android (eg opening .apk in SD card)

I tried flashing the ROM for 2 times and with a different SD card. Also I formatted the SD using Panasonic SD formatter and partitioned properly. The problem still appear after several access under disk drive mode. Million thanks!!!

voncrane said:

Memory cards get weak after awhile...Had d same issue with a Memory card...it works well on WinMo but messes up just as u described in android after a format n a few read & writes...Froyo has also been reported to ruin memory cards...Summary, there's no real solution as i've googled all over....My advice is for you 2 get a new memory card, capacity & class (d higher d number, d better its read & write speed) is up to you...I'm using a class (4) 8GB card n its been alright.
P.S. Stop transferring files via d disk drive option in android..stick to using memory card readers or d MAGDLR function (though some also report file errors with dis).

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Thanks for your reply
But how come windows and wm can read and write normally but it doesn't work in android?

Also, I have been using NAND and its disk drive option to transfer file in Cotulla's desire stock Rom and there is no problem at all. Would the problem be related to app2sd since the card has a ext4 partition?

voncrane said:

Try a chkdsk as well...But in my experience, i did it several times & it only acted as a band-aid...As it reverts to read only ltr on...

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So is this a SD card problem or ROM problem?
Previously I had been using Cotulla Desire stock Rom for a month and the problem didn't exist.

I don't mind buying a new SD card if it can completely solve the problem. Thanks