SD card loses write permission suddenly


In my FP2 with recent Fairphone OS (not rooted) I have a SanDisk Extreme Pro 128 GB card installed. It is used to store documents, pictures and downloaded files. There are no apps installed on it.

In principle it works - but it happens again and again that suddenly nothing (pictures, downloads, etc) can be written on the SD card. From the camera I get an error message and some apps which are using SD card as cache. So far I haven’t found out when write permission is lost.

After a reboot of FP2 everything is normal again but later (minutes, hours) the issue is back again.

BTW The thread SD Card no writing permission in FP2 didn’t really help.

Any idea?

Have you checked your sd card and its filesystem for errors?

Maybe use a card reader for doing this.

Also check here if your sd card generally is listed as “working” with FP2.

Thanks a lot.

I see quite strange things: Under Windows 7 the SD card isn’t recognized.

Under Linux the card is recognized with filesystem “vfat” and “read-only” and only with half the memory size.

But as I remember I did the format of the card with the FP2. So I formated it as “system memory” not only data memory because I thought to install apps on the card. But this didn’t work correctly - app icons are getting lost. So I used the card ony for text, pictures, audio files.

My idea now to continue: Copy all data to my Linux machine, reformat the SD card with FAT32 and restore the data on the card.

Should this work?

You can’t use FAT32 on 128 GB. You’re using exFAT (which is patented by Microsoft).

As for this card, you still need to ensure you have backups. Normal (micro)SD cards are prone to failure. If you want better data integrity, go for an industrial grade (micro)SD card. They’re more expensive though (estimation: at the lower ranges of 16-64 GB more than 2-3x the price). I’d say that for a smartphone it isn’t worth it though. But it is all the more reason to ensure you have backups.

Unless you can.
My 128 GB SD card runs happily with FAT32.


It doesn’t read like you actually formated it with your Fairphone 2.
Generally you ought to format it with your phone. Vfat sounds uncommon for any Android version.

As system memory as I know for Marshmallow+ it should be automatically encrypted and not accessible external by any tool/OS.
I am not sure if app installation should work in both format ways (internal systems storage or external [portable] unencrypted).
Backing up the data and re-formatting (in the phone) seems to be the best way here.

Test if the data is so far uncorrupted before you backup, not to have garbage only for restoring later. :neutral_face:
Maybe try both ways, using an external sd card reader and also accessing by establishing an usb connection.

1 Like

Could be that’s just how FAT filesystems get reported when queried in Linux environments. Android and TWRP are using Linux kernels, TWRP at least reports “vfat” for my FAT32 SD card.

Maybe something else: High temperature.

I have noticed now two times when SD loses the write permission: FP2 got very hot (some longer downloads via WiFi or data network) - exactly that zone where the card is plugged in.

I need to keep a close eye on this.

1 Like

Could be it. I also get error often when I boot up, that the microSD cannot be found. After boot it is right there.

Since about a week I observe a similar problem: my SD card (SanDisk Ultra 64GB microSDXC) had been working fine for more than two years but a week ago I suddenly lost the permission to write.

Even stranger: if I unmount my SD card and mount it again (or re-boot my FP2, respectively) IT SEEMS that I have write access for about one minute. I can delete files without error message and the files SEEMS to be deleted. After this minute, I observe all error messages again and must note that the files are still there.

Sounds like your SD card is dying.

1 Like

This topic was automatically closed 182 days after the last reply. New replies are no longer allowed.