I’m not definite that this is the end all be all solution for this, but with the new Market push came some issues that happened on my Droid.
It didn’t happen all right at once, so I assume it was some new SDK updates. In any case, several of my apps wouldn’t update and would give a “general error -18” whenever they did try to update.
Annoyed, I went to the web for an answer but couldn’t find one. People ran into the issue but no one had a solution. Which baffled me. Then I woke up from a tiring night of work and it hit me. All the apps that were having an issue were on my SD card.
Could it be as simple as that? So I moved the apps back onto the phone, hit update and voila! No error.
So the error happens when the app is partially on the SD card. To work around it, you have to move it back onto the phone and update.
Definitely something that Google needs to fix on Android but it’s good to finally have all my apps updated.