JOSM complaints about faults but the screen stays empty. so no restaurations possible.

[Hendrikklaas]

What steps will reproduce the problem?

1. Saving some data 4000 - 9000 nodes, but most of the time the remarks are not mine.

What is the expected result? nothing but still unanble to save.

What happens instead?

Please provide any additional information below. Attach a screenshot if possible.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-07-30 12:44:04 +0200 (Thu, 30 Jul 2020)
Build-Date:2020-07-31 01:30:49
Revision:16812
Relative:URL: ^/trunk

Identification: JOSM/1.5 (16812 nl) Windows 10 64-Bit
OS Build number: Windows 10 Home 1903 (18362)
Memory Usage: 247 MB / 989 MB (172 MB allocated, but free)
Java version: 1.8.0_261-b12, Oracle Corporation, Java HotSpot(TM) Client VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920x1080 (scaling 1.0x1.0)
Maximum Screen Size: 1920x1080
Best cursor sizes: 16x16 -> 32x32, 32x32 -> 32x32

Last errors/warnings:
- E: Handled by bug report queue: org.openstreetmap.josm.tools.JosmRuntimeException: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Cannot modify the id counter backwards. Oorzaak: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Cannot modify the id counter backwards. Oorzaak: java.lang.IllegalArgumentException: Cannot modify the id counter backwards


=== REPORTED CRASH DATA ===
BugReportExceptionHandler#handleException:
No data collected.

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: main (1)
org.openstreetmap.josm.tools.JosmRuntimeException: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Cannot modify the id counter backwards
	at org.openstreetmap.josm.spi.lifecycle.Lifecycle.initialize(Lifecycle.java:89)
	at org.openstreetmap.josm.gui.MainApplication.mainJOSM(MainApplication.java:915)
	at org.openstreetmap.josm.gui.MainApplication$3.processArguments(MainApplication.java:276)
	at org.openstreetmap.josm.gui.MainApplication.main(MainApplication.java:713)
Caused by: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Cannot modify the id counter backwards
	at java.util.concurrent.FutureTask.report(Unknown Source)
	at java.util.concurrent.FutureTask.get(Unknown Source)
	at org.openstreetmap.josm.spi.lifecycle.Lifecycle.initialize(Lifecycle.java:78)
	... 3 more
Caused by: java.lang.IllegalArgumentException: Cannot modify the id counter backwards
	at org.openstreetmap.josm.data.osm.UniqueIdGenerator.advanceUniqueId(UniqueIdGenerator.java:38)
	at org.openstreetmap.josm.io.AbstractReader.buildPrimitive(AbstractReader.java:627)
	at org.openstreetmap.josm.io.AbstractReader.addNode(AbstractReader.java:638)
	at org.openstreetmap.josm.io.AbstractReader.parseNode(AbstractReader.java:680)
	at org.openstreetmap.josm.io.OsmReader.parseNode(OsmReader.java:230)
	at org.openstreetmap.josm.io.OsmReader.parseOsm(OsmReader.java:169)
	at org.openstreetmap.josm.io.OsmReader.parseRoot(OsmReader.java:135)
	at org.openstreetmap.josm.io.OsmReader.parse(OsmReader.java:121)
	at org.openstreetmap.josm.io.OsmReader.lambda$doParseDataSet$0(OsmReader.java:491)
	at org.openstreetmap.josm.io.AbstractReader.doParseDataSet(AbstractReader.java:298)
	at org.openstreetmap.josm.io.OsmReader.doParseDataSet(OsmReader.java:488)
	at org.openstreetmap.josm.io.OsmReader.parseDataSet(OsmReader.java:538)
	at org.openstreetmap.josm.io.OsmReader.parseDataSet(OsmReader.java:521)
	at org.openstreetmap.josm.tools.Territories.initializeInternalData(Territories.java:137)
	at org.openstreetmap.josm.tools.Territories.initialize(Territories.java:123)
	at org.openstreetmap.josm.gui.MainInitialization.lambda$parallelInitializationTasks$6(MainInitialization.java:114)
	at org.openstreetmap.josm.spi.lifecycle.InitializationTask.call(InitializationTask.java:33)
	at org.openstreetmap.josm.spi.lifecycle.InitializationTask.call(InitializationTask.java:11)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

[Klumbumbus]

Closed as duplicate of #19532.