diff --git a/scripts/detect_regressions.py b/scripts/detect_regressions.py
index 8f2dd8a961d1d30bb019481770d05b8f45202b9d..8ee38f9d6a5d26d2ecc2c707e3eee5cf20d94669 100644
--- a/scripts/detect_regressions.py
+++ b/scripts/detect_regressions.py
@@ -61,7 +61,7 @@ def main(args):
         rng = result.columns[3:]  # Whole history
     else:
         rng = result.columns[-days:]
-    result = result.dropna(subset=rng)
+    result = result.dropna(subset=rng, how="all")
     result = result.reset_index(drop=True)
 
     ratio = result.copy()
@@ -87,15 +87,19 @@ def main(args):
         currdate = dates[-(days - i)]  # Make robust for shorter history
         prevdate = dates[-(days - i + 1)]
 
-        idx = ratio.groupby("format")[currdate].idxmax()
-        all_indices.extend(idx.tolist())
-
-        # Store worst case per format for plotting
-        for f in formats:
-            plotdata.loc[f, currdate] = ratio.iloc[idx[f]][currdate]
-            plottext.loc[f, currdate] = (
-                f"Job: {result.iloc[idx[f]]['job']}<br>Testcase: {result.iloc[idx[f]]['testcase']} <br>Max {measure} ratio: {ratio.iloc[idx[f]][currdate]:.2f}<br>Date: {currdate}"
-            )
+        # Get max ratio per format, skip formats with no data on this date
+        col = ratio[["format", currdate]].dropna()
+        if not col.empty:            
+            idx = col.groupby("format")[currdate].idxmax()
+            all_indices.extend(idx.tolist())
+
+            # Store worst case per format for plotting
+            for f in formats: 
+                if f in idx.index:
+                    plotdata.loc[f, currdate] = ratio.iloc[idx[f]][currdate]
+                    plottext.loc[f, currdate] = (
+                        f"Job: {result.iloc[idx[f]]['job']}<br>Testcase: {result.iloc[idx[f]]['testcase']} <br>Max {measure} ratio: {ratio.iloc[idx[f]][currdate]:.2f}<br>Date: {currdate}"
+                    )
 
     fig = make_subplots(
         rows=5,