diff --git a/opal/services/fhir/tests/test_fhir.py b/opal/services/fhir/tests/test_fhir.py
index 8eb674ab4..ee17e8954 100644
--- a/opal/services/fhir/tests/test_fhir.py
+++ b/opal/services/fhir/tests/test_fhir.py
@@ -68,7 +68,7 @@ def test_init(self, mocker: MockerFixture) -> None:
 
     def test_init_invalid_private_key(self) -> None:
         """FHIRConnector initialization fails when an invalid private key is provided."""
-        with pytest.raises(ValueError, match='Could not deserialize key data\\. '):
+        with pytest.raises(ValueError, match='Unable to load PEM file'):
             FHIRConnector(
                 oauth_url='https://example.com/oauth',
                 fhir_url='https://example.com/fhir',
diff --git a/pyproject.toml b/pyproject.toml
index 10fd0f831..6e9f8c89c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ readme = "README.md"
 requires-python = "==3.14.4"
 dependencies = [
     "argon2-cffi==25.1.0",
-    "authlib==1.7.0",
+    "authlib==1.6.11",
     "crispy-bootstrap5==2026.3",
     "dj-rest-auth==7.2.0",
     "django==6.0.4",
diff --git a/uv.lock b/uv.lock
index 8479b547c..050348afb 100644
--- a/uv.lock
+++ b/uv.lock
@@ -100,7 +100,7 @@ docs = [
 [package.metadata]
 requires-dist = [
     { name = "argon2-cffi", specifier = "==25.1.0" },
-    { name = "authlib", specifier = "==1.7.0" },
+    { name = "authlib", specifier = "==1.6.11" },
     { name = "crispy-bootstrap5", specifier = "==2026.3" },
     { name = "dj-rest-auth", specifier = "==7.2.0" },
     { name = "django", specifier = "==6.0.4" },
@@ -333,15 +333,14 @@ wheels = [
 
 [[package]]
 name = "authlib"
-version = "1.7.0"
+version = "1.6.11"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "cryptography" },
-    { name = "joserfc" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/d9/82/4d0603f30c1b4629b1f091bb266b0d7986434891d6940a8c87f8098db24e/authlib-1.7.0.tar.gz", hash = "sha256:b3e326c9aa9cc3ea95fe7d89fd880722d3608da4d00e8a27e061e64b48d801d5", size = 175890, upload-time = "2026-04-18T11:00:28.559Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/28/10/b325d58ffe86815b399334a101e63bc6fa4e1953921cb23703b48a0a0220/authlib-1.6.11.tar.gz", hash = "sha256:64db35b9b01aeccb4715a6c9a6613a06f2bd7be2ab9d2eb89edd1dfc7580a38f", size = 165359, upload-time = "2026-04-16T07:22:50.279Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/ca/48/c954218b2a250e23f178f10167c4173fecb5a75d2c206f0a67ba58006c26/authlib-1.7.0-py2.py3-none-any.whl", hash = "sha256:e36817afb02f6f0b6bf55f150782499ddd6ddf44b402bb055d3263cc65ac9ae0", size = 258779, upload-time = "2026-04-18T11:00:26.64Z" },
+    { url = "https://files.pythonhosted.org/packages/57/2f/55fca558f925a51db046e5b929deb317ddb05afed74b22d89f4eca578980/authlib-1.6.11-py2.py3-none-any.whl", hash = "sha256:c8687a9a26451c51a34a06fa17bb97cb15bba46a6a626755e2d7f50da8bff3e3", size = 244469, upload-time = "2026-04-16T07:22:48.413Z" },
 ]
 
 [[package]]