I am a newer to use openSUSE. Recently I execute zypper update and found yast2 UI client cannot be launched. I can see the log in /var/log/YaST2/y2log:

2020-03-30 02:30:06 <1> linux-fjbu(26996) [Ruby] yast/wfm.rb:308 Call client /usr/share/YaST2/clients/sw_single.rb
2020-03-30 02:30:06 <1> linux-fjbu(26996) [Pkg] PkgModule.cc(instance):68 Redirecting ZYPP log to y2log
2020-03-30 02:30:07 <2> linux-fjbu(26996) [Ruby] yast/i18n.rb:61 luocanwei debug: found:true; str:"Print the help for this module"
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Y2Ruby] binary/Y2RubyUtils.cc(y2_require):26 cannot require yast:undefined method `_' for FastGettext::Translation:Module at /usr/lib64/ruby/vendor_ruby/2.5.0/yast/i18n.rb:62:in `_'
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Y2Ruby] binary/Y2RubyUtils.cc(y2_require):26 cannot require yast:undefined method `message' for nil:NilClass at /usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import_pure'
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Y2Ruby] binary/Y2RubyComponent.cc(import):100 Reporting runtime error for import of module 'PackageCallbacks' message 'undefined method `message' for nil:NilClass'
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Interpreter] yast/i18n.rb:145 Runtime error when loading module 'PackageCallbacks'
2020-03-30 02:30:07 <2> linux-fjbu(26996) [Ruby] yast/builtins.rb:586 tostring builtin called on wrong type Class
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Ruby] yast/wfm.rb:253 Client /usr/share/YaST2/clients/sw_single.rb failed with 'Failed to load Module 'PackageCallbacks' due to: undefined method `message' for nil:NilClass' (RuntimeError).
Backtrace:
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import_pure'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import'
/usr/share/YaST2/modules/PackageCallbacks.rb:61:in `main'
/usr/share/YaST2/modules/PackageCallbacks.rb:3219:in `'
/usr/share/YaST2/modules/PackageCallbacks.rb:30:in `'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import_pure'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import'
/usr/share/YaST2/clients/sw_single.rb:24:in `main'
/usr/share/YaST2/clients/sw_single.rb:801:in `'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/wfm.rb:313:in `eval'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/wfm.rb:313:in `run_client'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/wfm.rb:206:in `call_builtin'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/wfm.rb:206:in `call_builtin_wrapper'
/usr/lib64/ruby/vendor_ruby/2.5.0/yast/wfm.rb:195:in `CallFunction'
/usr/lib/YaST2/bin/y2start:58:in `
'
2020-03-30 02:30:07 <3> linux-fjbu(26996) [Ruby] yast/wfm.rb:276 Internal error. Please report a bug report with logs.
Run save_y2logs to get complete logs.
Details: Failed to load Module 'PackageCallbacks' due to: undefined method `message' for nil:NilClass
Caller:  /usr/lib64/ruby/vendor_ruby/2.5.0/yast/yast.rb:186:in `import_pure'

I had report the bug https://bugzilla.suse.com/show_bug.cgi?id=1167315, but got no answer for a week.

How can I fix this problem. Thanks.