java.lang.IllegalArgumentException: cannot add to layout: constraint mu be a string (or null)

Searched on Google with the first line of a JAVA stack trace?

We can recommend more relevant solutions and speed up debugging when you paste your entire stack trace with the exception message. Try a sample exception.

Recommended solutions based on your search

Solutions on the web

via Oracle Community by 807554, 1 year ago
cannot add to layout: constraint mu be a string (or null)
via Stack Overflow by Flav
, 2 years ago
cannot add to layout: constraint must be a string (or null)
via dreamincode.net by Unknown author, 2 years ago
via Stack Overflow by user2278269
, 2 years ago
via Stack Overflow by Orlov Andrey
, 2 years ago
cannot add to layout: constraint must be a string (or null)
via Oracle Community by 843804, 1 year ago
cannot add to layout: constraint must be a string (or null)
java.lang.IllegalArgumentException: cannot add to layout: constraint mu be a string (or null)
at java.awt.BorderLayout.addLayoutComponent(BorderLayout.java:401)
at javax.swing.JRootPane$1.addLayoutComponent(JRootPane.java:453)
at java.awt.Container.addImpl(Container.java:482)
at java.awt.Container.add(Container.java:345)
at undefined.eMailFrame.add(eMail.java:118)
at undefined.eMailFrame.(eMail.java:67)
at undefined.eMail.main(eMail.java:12)

Users with the same issue

Once, 11 months ago
Samebug visitor profile picture
Unknown user
Once, 1 year ago

Write tip

Know the solutions? Share your knowledge to help other developers to debug faster.