This blog will explain the new transaction SM01_DEV and SM01_CUS, which are replacing the old SM01 transaction.
Questions that will be answered in this blog are:
- How does SM01_DEV work?
- How does SM01_CUS work?
- What are the differences between SM01_DEV and SM01_CUS?
SM01 transaction locking
In older SAP systems you can lock transaction for use with transaction SM01. In newer SAP systems you will get his message when using SM01:

This refers to new functions explained in oss note 2234192 – Enhancement to application start lock.
The new solution has 2 locking transactions: SM01_DEV for client independent locking and SM01_CUS for client dependent locking.
SM01_DEV locking transaction
Start tcode SM01_DEV:

In this example we will lock transaction SE30_OLD. On the next screen select the transaction and press the lock button. Fill out the transport number. End result:

When starting SE30_OLD you now get this error message:

SM01_CUS locking transaction
In this example we want to lock transaction S_ALR_87012271. The start screen is identical to SM01_DEV. If you want to lock the transaction you get a popup screen in which you can differentiate for WinGui or non WinGUI.

The transaction will be locked, but not be put into a transport. If you want to transport the lock, you have to use the transport button.
If OSS note 2470927 - SM01_CUS | API for application start lock does not work is not yet applied in the system you will face this error message after locking:Applying the note solves this issue.
After locking tcode S_ALR_87012271 and starting it you get this message now:

The transaction is now only locked in the local client. If you have more client or want a full central lock, then you have to run SM01_CUS from client 000.
Differences SM01_DEV and SM01_CUS
Differences between the 2 transactions:
- SM01_DEV locks global and has mandatory transport
- SM01_CUS locks per client and has an optional feature to transport
Bug fix oss notes
Bug fix OSS notes:
- 2927865 – SM01_CUS | Incorrect display of lock statuses in client 000
- 2979663 – SM01_CUS : Comment field cannot be edited
- 3075862 – SM01_CUS | Use with customer-specific selection masking
- 3091151 – Use SM01_CUS for background processing
Generic background note: 2234192 – Enhancement for locking application start