diff --git a/changelog.d/19839.bugfix b/changelog.d/19839.bugfix
new file mode 100644
index 0000000000..74606ce6f1
--- /dev/null
+++ b/changelog.d/19839.bugfix
@@ -0,0 +1 @@
+Fix the `/capabilities` endpoint returning a 500 error on non-media workers when [MSC4452: Preview URL capabilities API](https://github.com/matrix-org/matrix-spec-proposals/pull/4452) is enabled.
\ No newline at end of file
diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index cb50d0dc1d..373e518ddc 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -139,6 +139,10 @@ class ContentRepositoryConfig(Config):
     section = "media"
 
     def read_config(self, config: JsonDict, **kwargs: Any) -> None:
+        # We need to set this configuration flag even if this worker
+        # is not a media repo worker, as it's exposed in `/capabilities`
+        self.url_preview_enabled = bool(config.get("url_preview_enabled", False))
+
         # Only enable the media repo if either the media repo is enabled or the
         # current worker app is the media repo.
         if (
@@ -242,7 +246,6 @@ class ContentRepositoryConfig(Config):
         self.thumbnail_requirements = parse_thumbnail_requirements(
             config.get("thumbnail_sizes", DEFAULT_THUMBNAIL_SIZES)
         )
-        self.url_preview_enabled = bool(config.get("url_preview_enabled", False))
 
         if self.url_preview_enabled:
             check_requirements("url-preview")