From 1e1f0b7e1df2441dbdd5a133eee765c4d2b1839f Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Wed, 2 Apr 2025 11:01:42 -0600
Subject: [PATCH] Improve an error message.

---
 include/deal.II/lac/solver_minres.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/deal.II/lac/solver_minres.h b/include/deal.II/lac/solver_minres.h
index a2340082e7..1e0acecfdb 100644
--- a/include/deal.II/lac/solver_minres.h
+++ b/include/deal.II/lac/solver_minres.h
@@ -117,7 +117,12 @@ public:
   /**
    * Exception
    */
-  DeclException0(ExcPreconditionerNotDefinite);
+  DeclExceptionMsg(ExcPreconditionerNotDefinite,
+                   "The preconditioner for MinRes must be a symmetric and "
+                   "definite operator, even though MinRes can solve linear "
+                   "systems with symmetric and *indefinite* operators. "
+                   "During iterations, MinRes has detected that the "
+                   "preconditioner is apparently not definite.");
   /** @} */
 
 protected:
-- 
2.39.5