diff --git a/src/specify_cli/extensions/catalog/command_remove.py b/src/specify_cli/extensions/catalog/command_remove.py
index 23eb6d1214..80cc8cb33b 100644
--- a/src/specify_cli/extensions/catalog/command_remove.py
+++ b/src/specify_cli/extensions/catalog/command_remove.py
@@ -38,12 +38,19 @@ def catalog_remove(
             "[red]Error:[/red] Invalid catalog config: 'catalogs' must be a list."
         )
         raise typer.Exit(1)
+    for index, entry in enumerate(catalogs):
+        if not isinstance(entry, dict):
+            _commands.console.print(
+                f"[red]Error:[/red] Invalid catalog entry at index {index}: "
+                f"expected a mapping, got {type(entry).__name__}"
+            )
+            raise typer.Exit(1)
     safe_name = _escape_markup(name)
     original_count = len(catalogs)
     catalogs = [
         catalog
         for catalog in catalogs
-        if isinstance(catalog, dict) and catalog.get("name") != name
+        if catalog.get("name") != name
     ]
 
     if len(catalogs) == original_count:
diff --git a/tests/specify_cli/extensions/catalog/test_command_remove.py b/tests/specify_cli/extensions/catalog/test_command_remove.py
index 2892b09d20..d0c5f9e9ad 100644
--- a/tests/specify_cli/extensions/catalog/test_command_remove.py
+++ b/tests/specify_cli/extensions/catalog/test_command_remove.py
@@ -8,11 +8,47 @@
 import os
 from pathlib import Path
 
+import pytest
+import typer
 import yaml
 
 from tests.integrations.test_cli import _normalize_cli_output
 
 
+class TestExtensionCatalogRemoveValidation:
+    """Reject malformed entries before changing the user's catalog config."""
+
+    @pytest.mark.parametrize("invalid_entry", ["unfinished-entry", 0, False, None, []])
+    @pytest.mark.parametrize("invalid_index", [0, 1])
+    @pytest.mark.parametrize("target", ["keep", "does-not-exist"])
+    def test_malformed_entries_preserve_config(
+        self, tmp_path, monkeypatch, capsys, invalid_entry, invalid_index, target
+    ):
+        from specify_cli.extensions import _commands
+        from specify_cli.extensions.catalog.command_remove import catalog_remove
+
+        (tmp_path / ".specify").mkdir()
+        config_path = tmp_path / ".specify" / "extension-catalogs.yml"
+        entries = [{"name": "keep", "url": "https://example.com/team.json"}]
+        entries.insert(invalid_index, invalid_entry)
+        original = (
+            "# Local settings: café\n"
+            + yaml.safe_dump({"catalogs": entries, "metadata": "keep me"})
+        ).replace("\n", "\r\n").encode("utf-8")
+        config_path.write_bytes(original)
+        monkeypatch.setattr(_commands, "_require_specify_project", lambda: tmp_path)
+
+        with pytest.raises(typer.Exit) as exc_info:
+            catalog_remove(target)
+
+        assert exc_info.value.exit_code == 1
+        assert config_path.read_bytes() == original
+        output = _normalize_cli_output(capsys.readouterr().out)
+        assert f"Invalid catalog entry at index {invalid_index}" in output
+        assert f"expected a mapping, got {type(invalid_entry).__name__}" in output
+        assert "Removed catalog" not in output
+
+
 class TestExtensionCatalogRemoveCLI:
     """Integration coverage for the extension catalog command."""
 
@@ -34,6 +70,40 @@ def _invoke(self, argv, cwd):
         finally:
             os.chdir(old)
 
+    @pytest.mark.parametrize("target", ["keep", "does-not-exist"])
+    def test_remove_malformed_config_in_initialized_project(
+        self, tmp_path, target
+    ):
+        """A real initialized project keeps all config bytes on rejection."""
+        project = tmp_path / "initialized"
+        project.mkdir()
+        initialized = self._invoke(
+            [
+                "init", "--here", "--integration", "codex",
+                "--ignore-agent-tools", "--non-interactive", "--script", "py",
+            ],
+            project,
+        )
+        assert initialized.exit_code == 0, initialized.output
+        config_path = project / ".specify" / "extension-catalogs.yml"
+        original = (
+            "# Local settings: café\r\n"
+            "catalogs:\r\n"
+            "  - name: keep\r\n"
+            "    url: https://example.com/team.json\r\n"
+            "  - https://example.com/private.json\r\n"
+            "metadata: keep me\r\n"
+        ).encode("utf-8")
+        config_path.write_bytes(original)
+
+        result = self._invoke(["extension", "catalog", "remove", target], project)
+
+        assert result.exit_code == 1, result.output
+        assert config_path.read_bytes() == original
+        output = _normalize_cli_output(result.output)
+        assert "Invalid catalog entry at index 1: expected a mapping, got str" in output
+        assert "Removed catalog" not in output
+
     def test_extension_catalog_remove_rejects_non_mapping_config_root(self, tmp_path):
         project = self._make_project(tmp_path)
         cfg_path = project / ".specify" / "extension-catalogs.yml"