HTC Incredible says SMS storage is full, but it isn't My HTC Incredible refuses to let me view my SMS messages.  It will show the list of SMS senders, but when I click one to see their messages I get blocked by this popup:


  Unable to manage your messages because your storage is full.  Please
  delete content from other applications to make more space.


Of course I checked right away to see if I was using too much memory.  I went to Menu->Settings->SD &amp; Phone Storage and saw I have plenty of space:

SD card - Available space: 5.72GB

Internal phone storage - Available space: 6.25GB

Phone memory - Available space: 571MB

I have more free memory than used memory so that can't be the problem.  I tried restarting my phone as well but no change in message.  I also Googled the problem and among all the "me too" responses found that other have this problem where SMS is blocked even though they have plenty of memory.

I couldn't get a clear resolution and I'm worried the answers are now out of date.  ZDNet published a couple of articles on the issue:

Have I solved my Droid Incredible storage problem?

Is your Droid Incredible low on disk space?

Both suggest this is HTC's fault and that there is no fix.  They say you can try clearing the cache on HTC's apps like Peep, Messages and Mail and also advise clearing the cache on your browsers.

I've tried these techniques, but they didn't work.

Does anyone know what causes this and what solutions exist?
The Droid Incredible's available space for apps to store their data is only 150 MB, but it's impossible to view the amount of free app space on the stock ROM.  So the error message is correct, but you have no way to view the available free space.

In technical terms: /data/data is mounted on a different partition than /data, and all your free space views show you the amount of free space in the 750 MB /data partition.

What you need to do is start clearing data for spps that are taking up lots of space and that you don't use often.  One possibility is clearing the web browser's cache.  Facebook is another big data hog.  Check your other installed apps to see how much space they are using on data.

Here's a dump of the df -h output on my Inc:

Filesystem                Size      Used Available Use% Mounted on
tmpfs                   206.5M     32.0K    206.4M   0% /dev
tmpfs                   206.5M         0    206.5M   0% /mnt/asec
tmpfs                   206.5M         0    206.5M   0% /mnt/obb
/dev/block/mtdblock3    248.0M    121.8M    126.2M  49% /system
/dev/block/mmcblk0p1    748.0M    237.7M    472.3M  33% /data
/dev/block/mtdblock6    149.0M     79.7M     69.3M  54% /data/data
/dev/block/mmcblk0p2    193.7M     37.1M    146.5M  20% /cache
tmpfs                     8.0M         0      8.0M   0% /app-cache
/dev/block/vold/179:3     6.6G      1.2G      5.4G  18% /mnt/sdcard
/dev/block/vold/179:3     6.6G      1.2G      5.4G  18% /mnt/secure/asec
/dev/block/vold/179:9     1.8G    951.8M    930.1M  51% /mnt/emmc


(Note: I'm running a recent Cyanogenmod build that allows for swapping the SD Card and internal storage mount points -- that's why /mnt/sdcard is showing up as 6.6G while /mnt/emmc is only 1.8G.)

You can see how /data is a 750MB partition with plenty of free space, while /data/data is a teensy 150MB partition that's over half full.

This XDA Thread has a flashable mod that will make /data/data a subfolder of /data rather than a separate mount point, unlocking all that 750MB for app storage and allowing all your free space views to be accurate.  You'll need to root your phone in order for this to work since it also converts the filesystems to ext4 and that's going to require a replacement kernel.  (Recent Cyanogenmod builds already have this support, but if you're running the stock ROM you'll need to flash a different kernel.)