diff --git a/freqtrade/rpc/api_server/api_schemas.py b/freqtrade/rpc/api_server/api_schemas.py
index ca39b11fd..f1ac9db54 100644
--- a/freqtrade/rpc/api_server/api_schemas.py
+++ b/freqtrade/rpc/api_server/api_schemas.py
@@ -531,7 +531,7 @@ class BacktestHistoryEntry(BaseModel):
 
 class BacktestMetadataUpdate(BaseModel):
     strategy: str
-    notes: Optional[str]
+    notes: str = ''
 
 
 class SysInfo(BaseModel):