diff --git a/doc/release_notes.md b/doc/release_notes.md
index a14921cf77..6a2b9a305c 100644
--- a/doc/release_notes.md
+++ b/doc/release_notes.md
@@ -6,6 +6,8 @@
 <!-- Upcoming Release -->
 <!-- ================= -->
 
+* Fix: `lines: types` must now define a line type for the 380 kV level; the config validation fails early with a clear message instead of the workflow failing later ([#2166](https://github.com/PyPSA/pypsa-eur/issues/2166)).
+
 * Feature: New switches `industry: solid_biomass_for_industry_cc`, `industry: gas_for_industry_cc` and `industry: process_emissions_cc` to disable the carbon capture options for solid biomass for industry, gas for industry and industrial process emissions. All default to `true`, which matches the previous behaviour ([#2357](https://github.com/PyPSA/pypsa-eur/pull/2357)).
 
 * Feature: New option `sector: electrolysis` to allow hydrogen electrolysis to be configurable ([#2358](https://github.com/PyPSA/pypsa-eur/pull/2358)).
diff --git a/scripts/lib/validation/config/lines.py b/scripts/lib/validation/config/lines.py
index 125025f70c..e485e75d2c 100644
--- a/scripts/lib/validation/config/lines.py
+++ b/scripts/lib/validation/config/lines.py
@@ -10,7 +10,7 @@
 
 from typing import Literal
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from scripts.lib.validation.config._base import ConfigModel
 
@@ -89,3 +89,12 @@ class LinesConfig(BaseModel):
         default_factory=_DynamicLineRatingConfig,
         description="Configuration for dynamic line rating.",
     )
+
+    @field_validator("types")
+    @classmethod
+    def check_380_defined(cls, value: dict[float, str]) -> dict[float, str]:
+        if 380.0 not in value:
+            raise ValueError(
+                "`lines: types` must define a line type for the 380 kV voltage level."
+            )
+        return value
diff --git a/test/test_config_schema.py b/test/test_config_schema.py
index d6e8db1778..9d9d454a39 100644
--- a/test/test_config_schema.py
+++ b/test/test_config_schema.py
@@ -232,3 +232,15 @@ def test_config_file_is_valid(configfile):
     assert not invalid, f"Invalid config entries in {configfile}:\n" + "\n".join(
         f"  - {path}: {'; '.join(msgs)}" for path, msgs in invalid.items()
     )
+
+
+class TestLineTypes:
+    def test_default_defines_380kv(self):
+        config = validate_config({})
+        assert 380.0 in config.lines.types
+
+    def test_missing_380kv_is_rejected(self):
+        with pytest.raises(ValueError, match="380"):
+            validate_config(
+                {"lines": {"types": {220.0: "Al/St 240/40 2-bundle 220.0"}}}
+            )