diff --git a/changelog.d/7905.bugfix b/changelog.d/7905.bugfix
new file mode 100644
index 0000000000000000000000000000000000000000..e60e6244121098b52dbde8173918951fc855a0bc
--- /dev/null
+++ b/changelog.d/7905.bugfix
@@ -0,0 +1 @@
+Fix a longstanding bug when storing a media file with an empty `upload_name`.
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 69f353d46f9e3b7db9895e3f095dbba0e2ef298c..ae6822d6e742c73b15ff67d88785184da557cc59 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -139,7 +139,7 @@ class MediaRepository:
     async def create_content(
         self,
         media_type: str,
-        upload_name: str,
+        upload_name: Optional[str],
         content: IO,
         content_length: int,
         auth_user: str,
@@ -147,8 +147,8 @@ class MediaRepository:
         """Store uploaded content for a local user and return the mxc URL
 
         Args:
-            media_type: The content type of the file
-            upload_name: The name of the file
+            media_type: The content type of the file.
+            upload_name: The name of the file, if provided.
             content: A file like object that is the content to store
             content_length: The length of the content
             auth_user: The user_id of the uploader
@@ -156,6 +156,7 @@ class MediaRepository:
         Returns:
             The mxc url of the stored content
         """
+
         media_id = random_string(24)
 
         file_info = FileInfo(server_name=None, file_id=media_id)
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index 3ebf7a68e67395961d0d90f50b5915acc51b822a..d76f7389e101e7218c846f930aec74a7f5e97dd5 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -63,6 +63,10 @@ class UploadResource(DirectServeJsonResource):
                     msg="Invalid UTF-8 filename parameter: %r" % (upload_name), code=400
                 )
 
+        # If the name is falsey (e.g. an empty byte string) ensure it is None.
+        else:
+            upload_name = None
+
         headers = request.requestHeaders
 
         if headers.hasHeader(b"Content-Type"):