diff --git a/py/services/civitai_client.py b/py/services/civitai_client.py
index ed8a3c30..e64c4eeb 100644
--- a/py/services/civitai_client.py
+++ b/py/services/civitai_client.py
@@ -329,8 +329,19 @@ class CivitaiClient:
                     "name": result.get("name", ""),
                 }
             message = self._extract_error_message(result)
-            if message and "not found" in message.lower():
-                raise ResourceNotFoundError(f"Resource not found for model {model_id}")
+            if message and (
+                "not found" in message.lower()
+                or message.lower().startswith("no model with id ")
+            ):
+                raise ResourceNotFoundError(
+                    f"Civitai model {model_id} was not found. Check the original "
+                    "Civitai link: use the model ID from /models/<id>, not a "
+                    "version ID from ?modelVersionId=<id> or "
+                    "/api/download/models/<id>. If the model ID is correct, "
+                    "the model may have been removed or made inaccessible. "
+                    "If the page opens only when logged in, check the Civitai "
+                    "API key in LoRA Manager settings."
+                )
             if is_expected_offline_error(message):
                 logger.info("Civitai request skipped: %s", OFFLINE_FRIENDLY_MESSAGE)
                 return None
@@ -347,7 +358,7 @@ class CivitaiClient:
         except RateLimitError:
             raise
         except ResourceNotFoundError as exc:
-            logger.info("Model %s is no longer available on Civitai: %s", model_id, exc)
+            logger.info("Civitai model lookup failed: %s", exc)
             raise
         except Exception as e:
             logger.error("Error fetching model versions: %s", e, exc_info=True)
diff --git a/py/utils/civitai_utils.py b/py/utils/civitai_utils.py
index ceacdc77..3a232ded 100644
--- a/py/utils/civitai_utils.py
+++ b/py/utils/civitai_utils.py
@@ -148,7 +148,8 @@ def extract_civitai_model_url_parts(
     if parsed is None:
         return None, None
 
-    path_match = re.search(r"/models/(\d+)", parsed.path)
+    # Download URLs contain version IDs, not model IDs.
+    path_match = re.match(r"^/models/(\d+)(?:/|$)", parsed.path)
     if not path_match:
         return None, None
 
diff --git a/static/js/utils/civitaiUtils.js b/static/js/utils/civitaiUtils.js
index 2f7f30fd..7f5bb2a4 100644
--- a/static/js/utils/civitaiUtils.js
+++ b/static/js/utils/civitaiUtils.js
@@ -228,12 +228,19 @@ export function extractCivitaiModelUrlParts(url) {
 
     try {
         const parsedUrl = new URL(url);
+        if (parsedUrl.protocol !== 'http:' && parsedUrl.protocol !== 'https:') {
+            return { modelId: null, modelVersionId: null };
+        }
         if (!isSupportedCivitaiPageHost(parsedUrl.hostname)) {
             return { modelId: null, modelVersionId: null };
         }
 
-        const pathMatch = parsedUrl.pathname.match(/\/models\/(\d+)/);
-        const modelId = pathMatch ? pathMatch[1] : null;
+        // Download URLs contain version IDs, not model IDs.
+        const pathMatch = parsedUrl.pathname.match(/^\/models\/(\d+)(?:\/|$)/);
+        if (!pathMatch) {
+            return { modelId: null, modelVersionId: null };
+        }
+        const modelId = pathMatch[1];
         const modelVersionId = parsedUrl.searchParams.get('modelVersionId');
 
         return { modelId, modelVersionId };
@@ -269,8 +276,11 @@ export function classifyModelRelinkUrl(url) {
     }
 
     const hostname = parsedUrl.hostname.toLowerCase().replace(/^www\./, '');
-    const pathMatch = parsedUrl.pathname.match(/\/models\/(\d+)/);
-    const modelId = pathMatch ? pathMatch[1] : null;
+    const pathMatch = parsedUrl.pathname.match(/^\/models\/(\d+)(?:\/|$)/);
+    if (!pathMatch) {
+        return { source: null, modelId: null, modelVersionId: null };
+    }
+    const modelId = pathMatch[1];
     const modelVersionId = parsedUrl.searchParams.get('modelVersionId');
 
     if (SUPPORTED_CIVITAI_PAGE_HOSTS.has(hostname)) {
diff --git a/tests/frontend/utils/civitaiUtils.test.js b/tests/frontend/utils/civitaiUtils.test.js
index 04ae081e..36de32cd 100644
--- a/tests/frontend/utils/civitaiUtils.test.js
+++ b/tests/frontend/utils/civitaiUtils.test.js
@@ -352,6 +352,12 @@ describe('civitaiUtils', () => {
     });
 
     describe('extractCivitaiModelUrlParts', () => {
+        it.each(['civitai.com', 'civitai.red'])('rejects download and API URLs on %s', (host) => {
+            for (const path of ['/api/download/models/3390681', '/api/v1/models/3390681', '/models/3390681invalid']) {
+                expect(extractCivitaiModelUrlParts(`https://${host}${path}?modelVersionId=3390681`))
+                    .toEqual({ modelId: null, modelVersionId: null });
+            }
+        });
         it('extracts model and version ids from civitai.red model URLs', () => {
             expect(
                 extractCivitaiModelUrlParts('https://civitai.red/models/65423/name?modelVersionId=98765')
@@ -376,6 +382,12 @@ describe('civitaiUtils', () => {
     });
 
     describe('classifyModelRelinkUrl', () => {
+        it.each(['civitai.com', 'civitai.red', 'civarchive.com'])('rejects non-model pages on %s', (host) => {
+            for (const path of ['/api/download/models/3390681', '/api/v1/models/3390681', '/models/3390681invalid']) {
+                expect(classifyModelRelinkUrl(`https://${host}${path}`))
+                    .toEqual({ source: null, modelId: null, modelVersionId: null });
+            }
+        });
         it('classifies civitai.com model URLs', () => {
             expect(
                 classifyModelRelinkUrl('https://civitai.com/models/649516/name?modelVersionId=726676')
diff --git a/tests/services/test_civitai_client.py b/tests/services/test_civitai_client.py
index a023ee23..8689a60c 100644
--- a/tests/services/test_civitai_client.py
+++ b/tests/services/test_civitai_client.py
@@ -199,6 +199,26 @@ async def test_get_model_versions_raises_on_not_found(monkeypatch, downloader):
         await client.get_model_versions("missing")
 
 
+@pytest.mark.parametrize("payload", ["Resource not found", {"error": "No model with id 3390681"}])
+async def test_get_model_versions_not_found_explains_id_and_access(payload, downloader, caplog):
+    downloader.make_request = AsyncMock(return_value=(False, payload))
+    client = await CivitaiClient.get_instance()
+
+    with caplog.at_level("INFO"), pytest.raises(ResourceNotFoundError) as exc_info:
+        await client.get_model_versions("3390681")
+
+    message = str(exc_info.value)
+    assert "3390681" in message
+    assert "/models/<id>" in message
+    assert "modelVersionId" in message
+    assert "/api/download/models/<id>" in message
+    assert "API key" in message
+    assert "no longer available" not in caplog.text
+    downloader.make_request.assert_awaited_once_with(
+        "GET", f"{client.base_url}/models/3390681", use_auth=True
+    )
+
+
 async def test_get_model_versions_raises_on_nested_not_found(monkeypatch, downloader):
     async def fake_make_request(method, url, use_auth=True, **kwargs):
         return False, {"error": {"message": "Resource not found"}}
diff --git a/tests/utils/test_civitai_utils.py b/tests/utils/test_civitai_utils.py
index 6ef5362a..6b3bbc05 100644
--- a/tests/utils/test_civitai_utils.py
+++ b/tests/utils/test_civitai_utils.py
@@ -1,3 +1,5 @@
+import pytest
+
 from py.utils.civitai_utils import (
     build_license_flags,
     extract_civitai_image_id,
@@ -8,6 +10,13 @@ from py.utils.civitai_utils import (
     resolve_license_payload,
 )
 
+@pytest.mark.parametrize("host", ["civitai.com", "civitai.red"])
+@pytest.mark.parametrize("path", ["/api/download/models/3390681", "/api/v1/models/3390681", "/models/3390681invalid"])
+def test_extract_civitai_model_url_parts_rejects_non_model_pages(host, path):
+    assert extract_civitai_model_url_parts(
+        f"https://{host}{path}?modelVersionId=3390681"
+    ) == (None, None)
+
 
 def test_resolve_license_payload_defaults():
     payload, flags = resolve_license_info({})