Created an unreadable/unuploadable file

[osm@…]

What steps will reproduce the problem?

I was doing an import that requires merging objects (ways/relations) from one layer to another. I was doing it using the Conflate plugin and some of it using Edit/Merge selection. Not sure exactly what action made the layer invalid.

What is the expected result?

Being able to open the file and to upload it

What happens instead?

I was unable to upload the file (got a cryptic message described in #25022), reported it like is described in Help/ErrorMessages, saved the merged layer as file and called it a day. Today I tried opening that file and got a simular message to upload one ("Relation with external id '-491' refers to a missing primitive with external id '-621'")

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

I would've attached the corrupted file, but can't really find an option to do so.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2026-11-04 14:01:56 +0100 (Wed, 04 Nov 2026)
Revision:19678
Build-Date:2026-11-07 02:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (19678 en) Linux NixOS 26.11 (Zokor)
Memory Usage: 428 MB / 7812 MB (228 MB allocated, but free)
Java version: 21.0.13.0.2+1-nixos, N/A, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 2560x1440x[Multi depth]@180Hz (scaling 1.00×1.00) :0.1 2560x1440x[Multi depth]@144Hz (scaling 1.00×1.00)
Maximum Screen Size: 2560×1440
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_US.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_US
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: Hyprland
VM arguments: [--add-exports=java.base/sun.security.action=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.spi=ALL-UNNAMED, -Djosm.restart=true, -Djava.net.useSystemProxies=true, -Dawt.useSystemAAFontSettings=gasp]

Plugins:
+ Mapillary (1822)
+ OpeningHoursEditor (36493)
+ PicLayer (275)
+ ReplaceRelations (1.0)
+ Review.Changes (1.1.1)
+ RoadSigns (36503)
+ account_manager (0.3.2)
+ apache-commons (36483)
+ buildings_tools (36503)
+ conflation (280)
+ ejml (36483)
+ geotools (36483)
+ gridify (61)
+ jackson (36502)
+ jaxb (36483)
+ jdsp (1791284839)
+ jogl (1.2.3)
+ jts (36483)
+ log4j (36483)
+ multipoly-gone (0.9.0.0)
+ notesolver (0.5.0)
+ opendata (36503)
+ openqa (116)
+ panoramax (8)
+ pt_assistant (685)
+ reverter (36503)
+ scripting (v0.4.3)
+ splinex (36483)
+ turnrestrictions (36503)
+ utilsplugin2 (36503)
+ wikipedia (448)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/Wikidata&zip=1
+ https://github.com/baltpeter/id-tagging-schema-to-josm/releases/latest/download/id-presets-en-light.zip
+ ${HOME}/Code/PopulationPreset.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/LaneAttributes&zip=1

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/SidewalksAndFootways&zip=1
- https://github.com/osmlab/applepaintstyles/archive/main.zip
+ https://josm.openstreetmap.de/josmfile?page=Styles/iD&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1

Last errors/warnings:
- 00000.633 W: Missing plugin main version in plugin mapwithai
- 00001.019 W: Missing plugin main version in plugin mapwithai
- 00032.751 E: org.openstreetmap.josm.io.IllegalDataException: Relation with external id '-491' refers to a missing primitive with external id '-621'.
- 00032.756 E: Error - <html>Could not read file 'GlavniTrg.osm'.<br>Error is:<br>Relation with external id '-491' refers to a missing primitive with external id '-621'.</html>

[osm@…]

Corrupted file. Data from it isn't uploaded to OSM yet