How can I do with a validation rule so that, for example, from the New state I only get to click Assigned. The rest of the states should give an error message or blocked (I don't know if it can be blocked)

CodePudding user response：

Read up about PRIORVALUE() function, for example https://developer.salesforce.com/forums/?id=906F00000008pFfIAI

Something like this should do the trick

ISCHANGED(Status)
&& ISPICKVAL(PRIORVALUE(Status), 'New') 
&& !ISPICKVAL(Status, 'Assigned')

This is also an interesting take: https://trailhead.salesforce.com/trailblazer-community/feed/0D54S00000A7SPhSAN