A question I have been asked time and time again is from users trying to install my apps only to see something like:
- Unknown error / reason -18
- Can’t install to usb or sd card
Unfortunately developers don’t have access to any installation process hooks so problems like these are invariably with the Android Market app and not the app that the user is trying to install.
In all cases so far the solution has been simple:
- Mount your sd card in disk drive mode on your phone.
- On your computer delete the .android_secure/smd12tmp1.asec file. Note the leading dot may cause the directory to be hidden so enable hidden files in your file manager to see it.
- On your computer safely remove / eject the mounted disk drive.
- On your phone disable the disk drive mode.
- Try to install the app again.
It would be nice if Google would come up with a more descriptive error message but until then this should work.