diff --git a/pyomo/contrib/appsi/solvers/cbc.py b/pyomo/contrib/appsi/solvers/cbc.py
index 9b8fa3e0e57..ec1819e29e7 100644
--- a/pyomo/contrib/appsi/solvers/cbc.py
+++ b/pyomo/contrib/appsi/solvers/cbc.py
@@ -70,7 +70,7 @@ def __init__(
         self.executable = Executable('cbc')
         self.filename = None
         self.keepfiles = False
-        self.solver_output_logger = logger
+        self.solver_output_logger = None
         self.log_level = logging.INFO
 
 
@@ -389,11 +389,13 @@ def _check_and_escape_options():
         cmd.extend(['-solve'])
         cmd.extend(['-solu', self._filename + '.soln'])
 
-        ostreams = [
-            LogStream(
-                level=self.config.log_level, logger=self.config.solver_output_logger
+        ostreams = []
+        if self.config.solver_output_logger is not None:
+            ostreams.append(
+                LogStream(
+                    level=self.config.log_level, logger=self.config.solver_output_logger
+                )
             )
-        ]
         if self.config.stream_solver:
             ostreams.append(sys.stdout)
 
diff --git a/pyomo/contrib/appsi/solvers/cplex.py b/pyomo/contrib/appsi/solvers/cplex.py
index 9061f063ab7..87caab22889 100644
--- a/pyomo/contrib/appsi/solvers/cplex.py
+++ b/pyomo/contrib/appsi/solvers/cplex.py
@@ -64,7 +64,7 @@ def __init__(
 
         self.filename = None
         self.keepfiles = False
-        self.solver_output_logger = logger
+        self.solver_output_logger = None
         self.log_level = logging.INFO
 
 
@@ -253,18 +253,27 @@ def _apply_solver(self, timer: HierarchicalTimer):
         cplex_model.read(self._filename + '.lp')
         timer.stop('cplex read lp')
 
-        log_stream = LogStream(
-            level=self.config.log_level, logger=self.config.solver_output_logger
-        )
-        if config.stream_solver:
+        if config.solver_output_logger is not None:
+            log_stream = LogStream(
+                level=self.config.log_level, logger=self.config.solver_output_logger
+            )
+        else:
+            log_stream = None
 
-            def _process_stream(arg):
-                sys.stdout.write(arg)
-                return arg
+        def _process_stream(arg):
+            sys.stdout.write(arg)
+            return arg
 
-            cplex_model.set_results_stream(log_stream, _process_stream)
+        if config.stream_solver:
+            if log_stream is not None:
+                cplex_model.set_results_stream(log_stream, _process_stream)
+            else:
+                cplex_model.set_results_stream(sys.stdout)
         else:
-            cplex_model.set_results_stream(log_stream)
+            if log_stream is not None:
+                cplex_model.set_results_stream(log_stream)
+            else:
+                cplex_model.set_results_stream(None)
 
         for key, option in self.cplex_options.items():
             opt_cmd = cplex_model.parameters
diff --git a/pyomo/contrib/appsi/solvers/gurobi.py b/pyomo/contrib/appsi/solvers/gurobi.py
index b8048f26f3c..84e806ad73f 100644
--- a/pyomo/contrib/appsi/solvers/gurobi.py
+++ b/pyomo/contrib/appsi/solvers/gurobi.py
@@ -86,7 +86,7 @@ def __init__(
         self.declare('log_level', ConfigValue(domain=NonNegativeInt))
 
         self.logfile = ''
-        self.solver_output_logger = logger
+        self.solver_output_logger = None
         self.log_level = logging.INFO
 
 
@@ -359,11 +359,13 @@ def symbol_map(self):
         return self._symbol_map
 
     def _solve(self, timer: HierarchicalTimer):
-        ostreams = [
-            LogStream(
-                level=self.config.log_level, logger=self.config.solver_output_logger
+        ostreams = []
+        if self.config.solver_output_logger is not None:
+            ostreams.append(
+                LogStream(
+                    level=self.config.log_level, logger=self.config.solver_output_logger
+                )
             )
-        ]
         if self.config.stream_solver:
             ostreams.append(sys.stdout)
 
diff --git a/pyomo/contrib/appsi/solvers/highs.py b/pyomo/contrib/appsi/solvers/highs.py
index edaafa5d1d4..df3d58ba320 100644
--- a/pyomo/contrib/appsi/solvers/highs.py
+++ b/pyomo/contrib/appsi/solvers/highs.py
@@ -71,7 +71,7 @@ def __init__(
         self.declare('log_level', ConfigValue(domain=NonNegativeInt))
 
         self.logfile = ''
-        self.solver_output_logger = logger
+        self.solver_output_logger = None
         self.log_level = logging.INFO
 
 
@@ -248,11 +248,13 @@ def _solve(self, timer: HierarchicalTimer):
         config = self.config
         options = self.highs_options
 
-        ostreams = [
-            LogStream(
-                level=self.config.log_level, logger=self.config.solver_output_logger
+        ostreams = []
+        if config.solver_output_logger is not None:
+            ostreams.append(
+                LogStream(
+                    level=self.config.log_level, logger=self.config.solver_output_logger
+                )
             )
-        ]
         if self.config.stream_solver:
             ostreams.append(sys.stdout)
 
@@ -272,7 +274,6 @@ def _solve(self, timer: HierarchicalTimer):
             if config.warmstart:
                 self._warm_start()
             timer.start('optimize')
-            ostreams[-1].write("RUN!\n")
             if self.version()[:2] >= (1, 8):
                 self._solver_model.HandleKeyboardInterrupt = True
             self._solver_model.run()
diff --git a/pyomo/contrib/appsi/solvers/ipopt.py b/pyomo/contrib/appsi/solvers/ipopt.py
index 601b830b7f2..161f5daa237 100644
--- a/pyomo/contrib/appsi/solvers/ipopt.py
+++ b/pyomo/contrib/appsi/solvers/ipopt.py
@@ -73,7 +73,7 @@ def __init__(
         self.executable = Executable('ipopt')
         self.filename = None
         self.keepfiles = False
-        self.solver_output_logger = logger
+        self.solver_output_logger = None
         self.log_level = logging.INFO
 
 
@@ -440,11 +440,13 @@ def _apply_solver(self, timer: HierarchicalTimer):
         else:
             timeout = None
 
-        ostreams = [
-            LogStream(
-                level=self.config.log_level, logger=self.config.solver_output_logger
+        ostreams = []
+        if self.config.solver_output_logger is not None:
+            ostreams.append(
+                LogStream(
+                    level=self.config.log_level, logger=self.config.solver_output_logger
+                )
             )
-        ]
         if self.config.stream_solver:
             ostreams.append(sys.stdout)
 
diff --git a/pyomo/contrib/appsi/solvers/maingo.py b/pyomo/contrib/appsi/solvers/maingo.py
index 8273061be78..63817551eb1 100644
--- a/pyomo/contrib/appsi/solvers/maingo.py
+++ b/pyomo/contrib/appsi/solvers/maingo.py
@@ -118,7 +118,7 @@ def __init__(
             ),
         )
         self.declare("logfile", ConfigValue(domain=str, default=""))
-        self.declare("solver_output_logger", ConfigValue(default=logger))
+        self.declare("solver_output_logger", ConfigValue(default=None))
         self.declare(
             "log_level", ConfigValue(domain=NonNegativeInt, default=logging.INFO)
         )
@@ -209,11 +209,13 @@ def symbol_map(self):
         return self._symbol_map
 
     def _solve(self, timer: HierarchicalTimer):
-        ostreams = [
-            LogStream(
-                level=self.config.log_level, logger=self.config.solver_output_logger
+        ostreams = []
+        if self.config.solver_output_logger is not None:
+            ostreams.append(
+                LogStream(
+                    level=self.config.log_level, logger=self.config.solver_output_logger
+                )
             )
-        ]
         if self.config.stream_solver:
             ostreams.append(sys.stdout)