Can't create user account without password via J-Web on SRX5400 2nd generation 

Can't create user account without password via J-Web on SRX5400 2nd generation. Once clicked the save button for newly created user without password via J-Web, it gave the following error message:

The configuration could not be locked. 

Error(s): 

1): failed to create user due to invalid password' 

The issue could be replicated on different Junos OS: 20.4R3-S3.4/20.4R3-S9.3/21.4R3-S10/21.4R3-S11.3.

However, Junos 21.4 reached EOE and bug fix is no longer provided, therefore no fix for this issue.

A workaround is to configure new users without password using CLI:

# set system login user <user name> uid <UID number>

# set system login user <user name> class <class name>