Cannot open system clippboard in SwingClippboard.checkContentChanged

[herrgrossmann]

The following exception has been ocurred severel times, found in log. Cause for the exception is not yet clear.

Maybe this link helps: https://coderanch.com/t/377833/java/listen-clipboard

2018-03-20 12:05:19,883 [pool-6-thread-1] ERROR o.j.s.i.c.AbstractPollingClipboardObservableSpi - null
java.lang.IllegalStateException: cannot open system clipboard
at sun.awt.windows.WClipboard.openClipboard(Native Method)
at sun.awt.datatransfer.ClipboardTransferable.(ClipboardTransferable.java:78)
at sun.awt.datatransfer.SunClipboard.getContents(SunClipboard.java:143)
at org.jowidgets.spi.impl.swing.common.clipboard.SwingClipboard.checkContentChanged(SwingClipboard.java:107)
at org.jowidgets.spi.impl.clipboard.AbstractPollingClipboardObservableSpi$PollingExecutor.run(AbstractPollingClipboardObservableSpi.java:104)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)