diff --git a/cli/runners/all_pairs_cflr_tool_runner.py b/cli/runners/all_pairs_cflr_tool_runner.py
index b161d21..cb8b96d 100644
--- a/cli/runners/all_pairs_cflr_tool_runner.py
+++ b/cli/runners/all_pairs_cflr_tool_runner.py
@@ -1,6 +1,7 @@
 import re
 import shlex
 import subprocess
+import traceback
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from pathlib import Path
@@ -67,7 +68,24 @@ def run(self) -> CflrToolRunResult:
             stdout=subprocess.PIPE,
             text=True,
         )
-        return self.parse_results(process)
+        return self.safe_parse_results(process)
+
+    def safe_parse_results(self, process: subprocess.CompletedProcess[str]) -> CflrToolRunResult:
+        try:
+            return self.parse_results(process)
+        except Exception:
+            print(
+                "   Failed to parse results\n"
+                "   (interpreting as incompatible CFL-r tool error)"
+            )
+            print("=====")
+            print("stdout:\n" + process.stdout)
+            print("=====")
+            print("stderr:\n" + process.stderr)
+            print("=====")
+            traceback.print_exc()
+            print("=====")
+            raise IncompatibleCflrToolError()
 
     @abstractmethod
     def parse_results(self, process: subprocess.CompletedProcess[str]) -> CflrToolRunResult:
diff --git a/cli/runners/gigascale_algo_all_pairs_cflr_tool_runner.py b/cli/runners/gigascale_algo_all_pairs_cflr_tool_runner.py
index 1189e7a..d0d01ed 100644
--- a/cli/runners/gigascale_algo_all_pairs_cflr_tool_runner.py
+++ b/cli/runners/gigascale_algo_all_pairs_cflr_tool_runner.py
@@ -44,7 +44,7 @@ def run(self) -> CflrToolRunResult:
             expect eof
             """
         )
-        return self.parse_results(process)
+        return self.safe_parse_results(process)
 
     def parse_results(self, process: subprocess.CompletedProcess[str]) -> CflrToolRunResult:
         # parses a table like this: