The block is write-protected because an action....

Hi

Suddenly, sometimes my blocks gets write protected when I make changes.

When I make a change, this message is displayed. 

The block is write-protected because an action was undone. Redo the action or reopen the block to remove the write protection. 

Reopening the block is not solving the issue. 

Restarting TIA is solving the issue, until next time. 

Version 17 Update 5 

Hi ElonksuM_SN_BN

Nothing is copied from another project. 

I have tried to recompile all, but the issue is still there. 

I know this thread was from last year, but if anybody is curious as to how to solve the problem, Right click on the PLC/ Program Blocks Folder then Compile > Software (Rebuild all) 

This trick worked for me. Where the Main OB just randomly throws "The block is write protected because ..." warning after copying the project from a workstation to another one and then opening it.