Q: after upgraded to OSX EL Capitan to 10.11.15 all program are corrupted. this also happend when i tried 10.11.14.

It is generally recommended to check the applications compatibility and backup important settings/data before update.

Upgrade to OS X El Capitan - Apple Support

I would go further, thunderzzz, and say that it's not just generally recommended, it is always recommended.

To the OP:  Before you upgrade, make sure all your applications/plugins/extensions/drivers are compatible with El Capitan.  If they're not compatible, upgrade them so they are.  If they cannot be upgraded, uninstall them.  If you can't or don't want to uninstall them, don't upgrade.  Upgrading does not magically wipe out problems, it merely carries them over.

Your upgrade process was mangled somehow.

If you can, try downloading the 10.11.5 Combo Update and run it.

If that does not work, then you will need to reinstall the OS.

peterscartoons wrote:

 

Pinkstones, thunderzzz
The programmes are compatible.

the problem is that ALL the software give the error that they seem to be corrupted. Even preview and safari and iTunes.

 

the iMac is from 2011, that is not that old.

To continue off what Luis said, here is the link for the 10.11.5 Combo update --> Download OS X El Capitan 10.11.5 Combo Update

To reinstall the OS, should it come to that, you'd boot to the recovery screen (press Command + R after the startup chime) and select the option to reinstall OS X.  Make sure you have a constant Internet connection through the whole process.