Hands Off…

I wonder how many times someone stuck their finger into SAPMSSYD before the developer included this warning…

*///////////////////////////////////////////////////////////////////////
* C A U T I O N:
*///////////////////////////////////////////////////////////////////////
* If you want to add a specific handler within a main step handler,
* make sure to follow the following
* G O L D E N  R U L E
* If you do not know, what a dynpro is:    HANDS OFF
* If you do not know, what a main step is: HANDS OFF
...
* N E V E R  prototype here. You may damage the system seriously.
* The worst case will lead to a system, where nobody can login.
* It will be your job, to spend the following night in your office
* to repair the system.
*///////////////////////////////////////////////////////////////////////

The thing is that I discovered this comment late one night many years ago after implementing a login screen for RF scanners using SAP Console. The process is described in Note 365664. I ignored the part of the note that said “Please, change only the layout!!!!” and tried to include a subscreen or module(can’t remember why).

The result was that nobody could log into the system. The reason is that the code in the login program SAPMSYST is hidden(try to view it in SE80:-) ). As soon as this program is modified, the hidden code is lost(…it took me a while to figure out what the heck happened).

The only way to fix this error is to transport program SAPMSYST from a working system into the broken system.