So the one-line non-deprecated way would be: 

    Set sc=person.%JSONExportToString(.json), dynObj = {}.%FromJSON(json)
    
    // or if we have long objects
    
    Set sc=person.%JSONExportToStream(.json), dynObj = {}.%FromJSON(json)

But I agree it would be nicer to have just one command!, like the one that @Laura Blázquez García pointed out. 

Good catch! I tried to keep it short, but it was too vague—my bad! Thanks for pointing it out! 😄 (I edited the article with your comments) . Thanks!

The CSPSystem user has probably been disabled because it has not been active for so long. You can connect to the terminal and use the ^SECURITY routine to display all the users and check the ones disabled. 

If this doesn't work and you need access quickly, contact the WRC.