Many Apps on iphone 4s crash after updating to ios6 ..

It is a problem with compatibility. Normal~ wait for the fix in the next upgrade

I've also had the same issues, after upgrading to IOS 6.0, the apps in my iPhone 4 were crashing and the battery life run out very fast.

The only solution worked for me was to remove all mail accounts (Exchange/Gmail) from my iPhone (in settings) and then add them back.

The crashing were stopped! 🙂 also the battery was back to normal.

I found the solution by first looking at the crash logs (in IOS 6). you can find them at Settings -> General -> About (at the bottom of the About menu you will find the option that opens the logs).

There i saw many logs about Low Memory crash. 99% of the logs were pointed that the largest process (use the most memory) during the crashes is "dataaccessd".

I search in the web and found that this process is a deamon process that reponsible the Mail accounts (like Exchange/Gmail) and contancts list.

I've installed the app "System Status - activity monitor" which shows important system info like CPU usage, Memory usage and running processes.

Before apply my solution (deleting the mail accounts) i saw that the CPU usage was very high which consume the battery very fast. Also i saw that the memory (RAM) was run out.. which probably what cause the crashing..

After deleting the mail accounts (at Settings -> Mail, Contacts, Calendars) i check again with the System Status app, and saw that the memory and CPU were back to normal.

Adding the mail accounts back, still everything work ok 🙂

Hope this solution will help you too,

Enjoy! 🙂