Merge pull request #1825 from ethompsy/ISSUE-1472

ISSUE-1472: Added xcrun debugging tips to error message for failed signing attempts

Author: freakboy3742

changes/1472.misc.rst

@@ -0,0 +1 @@
+Added xcrun debugging tips to error message for failed signing attempts

src/briefcase/platforms/macOS/__init__.py

@@ -674,7 +674,18 @@ def notarize(self, filename, team_id):
                         store_credentials = True
                     else:
                         raise BriefcaseCommandError(
-                            f"Unable to submit {filename.relative_to(self.base_path)} for notarization."
+                            f"""\
+Unable to submit {filename.relative_to(self.base_path)} for notarization.
+To find the cause of this failure, get the submission ID by running:
+
+    xcrun notarytool history
+
+Then run:
+
+    xcrun notarytool log <submission-id>
+
+to generate a full log of the error.
+"""
                         ) from e
         finally:
             # Clean up house; we don't need the archive anymore.