GEOS 3.15: Splitting collections explodes the collection
Author: gacarrillorCreated Sep 17, 2026Updated Sep 17, 2026
LabelsBug
What is the bug or the crash?
References: https://github.com/libgeos/geos/issues/1482
This affects the expected results of the Split Features tool.
Should be a BLOCKER for the 4.4 release. ⚠️
Steps to reproduce the issue
A way to reproduce it without GUI interaction is by running this code snippet:
# Prepare layer geometry
vl = QgsVectorLayer("MultiLineString?crs=EPSG:4326", "Multis", "memory")
wkt = "MultiLineString ((0 5, 10 5),(10 5, 15 5),(15 5, 20 5)"
f = QgsFeature()
f.setGeometry(QgsGeometry.fromWkt(wkt))
vl.dataProvider().addFeature(f)
QgsProject.instance().addMapLayer(vl)
# Call split features
vl.startEditing()
split_curve = QgsLineString()
split_curve.fromWkt("LineString (4 4, 4 6)")
result, _ = vl.splitFeatures(split_curve, preserveCircular=False, topologicalEditing=False)
# Check result
# assert vl.featureCount() == 3 # No longer the case, now we get 4, as the multi geom is exploded
for feature in vl.getFeatures():
print(feature.geometry().asWkt())
# prints:
#LineString (0 5, 4 5)
#LineString (10 5, 15 5)
#LineString (15 5, 20 5)
#LineString (4 5, 10 5)
# we would expect:
# "MultiLineString ((10 5, 15 5),(15 5, 20 5)"
# "MultiLineString ((0 5, 4 5)"
# "MultiLineString ((4 5, 10 5)"
Versions
QGIS 4.4 running against GEOS 3.15
Supported QGIS version
- I'm running a supported QGIS version according to the roadmap.
New profile
- I tried with a new QGIS profile
No Duplicate of the Issue
- I have verified that there are no existing issues raised related to my problem.
Additional context
No response
Source: qgis/QGIS