Error saving JSON to database

I'm trying to save some configurations as JSON. I have one of the MySQL columns set as JSON datatype.
This script works in MySqlWorkbench:

UPDATE db_os_manf_dashboard.config
SET configvalue = '{"One": 1, "Two": 2}'
WHERE id = 4;

This fails in Designer's Script Console:

outJSON = {"One": 3, "Two": 4}
x = system.db.runPrepUpdate("UPDATE config SET configvalue = '?' WHERE id = ?", [outJSON, 2])
Traceback
Java Traceback:
Traceback (most recent call last):
  File "<input>", line 5, in <module>
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.error(AbstractDBUtilities.java:392)
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.runPrepUpdate(AbstractDBUtilities.java:268)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.base/java.lang.reflect.Method.invoke(Unknown Source)
java.lang.Exception: java.lang.Exception: Error executing system.db.runPrepUpdate(UPDATE config SET configvalue = '?' WHERE id = ?, [{'One': 3, 'Two': 4}, 2], , , false, false)

	at org.python.core.Py.JavaError(Py.java:547)
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.error(AbstractDBUtilities.java:392)
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.runPrepUpdate(AbstractDBUtilities.java:268)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.base/java.lang.reflect.Method.invoke(Unknown Source)
	at org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:190)
	at com.inductiveautomation.ignition.common.script.ScriptManager$ReflectedInstanceFunction.__call__(ScriptManager.java:552)
	at org.python.core.PyObject.__call__(PyObject.java:477)
	at org.python.core.PyObject.__call__(PyObject.java:481)
	at org.python.pycode._pyx53.f$0(<input>:6)
	at org.python.pycode._pyx53.call_function(<input>)
	at org.python.core.PyTableCode.call(PyTableCode.java:173)
	at org.python.core.PyCode.call(PyCode.java:18)
	at org.python.core.Py.runCode(Py.java:1687)
	at org.python.core.Py.exec(Py.java:1731)
	at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:277)
	at org.python.util.InteractiveInterpreter.runcode(InteractiveInterpreter.java:130)
	at com.inductiveautomation.ignition.designer.gui.tools.jythonconsole.JythonConsole$ConsoleWorker.doInBackground(JythonConsole.java:626)
	at com.inductiveautomation.ignition.designer.gui.tools.jythonconsole.JythonConsole$ConsoleWorker.doInBackground(JythonConsole.java:614)
	at java.desktop/javax.swing.SwingWorker$1.call(Unknown Source)
	at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
	at java.desktop/javax.swing.SwingWorker.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.Exception: Error executing system.db.runPrepUpdate(UPDATE config SET configvalue = '?' WHERE id = ?, [{'One': 3, 'Two': 4}, 2], , , false, false)
	... 26 more
Caused by: com.inductiveautomation.ignition.client.gateway_interface.GatewayException: Unable to decode arguments
	at com.inductiveautomation.ignition.client.gateway_interface.GatewayInterface.newGatewayException(GatewayInterface.java:351)
	at com.inductiveautomation.ignition.client.gateway_interface.GatewayInterface.sendMessage(GatewayInterface.java:325)
	at com.inductiveautomation.ignition.client.gateway_interface.GatewayInterface.sendMessage(GatewayInterface.java:278)
	at com.inductiveautomation.ignition.client.script.ClientDBUtilities._runPrepStmt(ClientDBUtilities.java:288)
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.runPrepUpdate(AbstractDBUtilities.java:261)
	... 24 more
Caused by: java.io.InvalidClassException: failed to read class descriptor
	at java.io.ObjectInputStream.readNonProxyDesc(null)
	at java.io.ObjectInputStream.readClassDesc(null)
	at java.io.ObjectInputStream.readOrdinaryObject(null)
	at java.io.ObjectInputStream.readObject0(null)
	at java.io.ObjectInputStream.readArray(null)
	at java.io.ObjectInputStream.readObject0(null)
	at java.io.ObjectInputStream.readObject(null)
	at java.io.ObjectInputStream.readObject(null)
	at com.inductiveautomation.ignition.common.Base64.decodeToObjectFragile(Base64.java:985)
	at com.inductiveautomation.ignition.gateway.servlets.gateway.functions.RunPrepStmt.runUpdateQuery(RunPrepStmt.java:43)
	at com.inductiveautomation.ignition.gateway.servlets.gateway.functions.AbstractUpdateQuery.run(AbstractUpdateQuery.java:25)
	at com.inductiveautomation.ignition.gateway.servlets.gateway.functions.AbstractDBAction.invoke(AbstractDBAction.java:66)
	at com.inductiveautomation.ignition.gateway.servlets.Gateway.doPost(Gateway.java:434)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:523)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
	at com.inductiveautomation.ignition.gateway.bootstrap.MapServlet.service(MapServlet.java:86)
	at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1410)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:764)
	at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1665)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:527)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:131)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:223)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1570)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:221)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1383)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:176)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:484)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1543)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:174)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1305)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:129)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
	at com.inductiveautomation.catapult.handlers.RemoteHostNameLookupHandler.handle(RemoteHostNameLookupHandler.java:121)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
	at org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:301)
	at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:51)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:141)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:122)
	at org.eclipse.jetty.server.Server.handle(Server.java:563)
	at org.eclipse.jetty.server.HttpChannel.lambda$handle$0(HttpChannel.java:505)
	at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:762)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:497)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:282)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:314)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:100)
	at org.eclipse.jetty.io.SelectableChannelEndPoint$1.run(SelectableChannelEndPoint.java:53)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.runTask(AdaptiveExecutionStrategy.java:416)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.consumeTask(AdaptiveExecutionStrategy.java:385)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.tryProduce(AdaptiveExecutionStrategy.java:272)
	at org.eclipse.jetty.util.thread.strategy.AdaptiveExecutionStrategy.lambda$new$0(AdaptiveExecutionStrategy.java:140)
	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:411)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:934)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1078)
	at java.lang.Thread.run(null)
Traceback (most recent call last):
  File "<input>", line 5, in <module>
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.error(AbstractDBUtilities.java:392)
	at com.inductiveautomation.ignition.common.script.builtin.AbstractDBUtilities.runPrepUpdate(AbstractDBUtilities.java:268)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.base/java.lang.reflect.Method.invoke(Unknown Source)
java.lang.Exception: java.lang.Exception: Error executing system.db.runPrepUpdate(UPDATE config SET configvalue = '?' WHERE id = ?, [{'One': 3, 'Two': 4}, 2], , , false, false)

Any ideas on the error?
Any comments on the whole approach of saving configuration as JSON?

Try using system.util.jsonEncode and passing the result of that to runPrepUpdate.

Thank you for the quick out-of-hours reply!

This seems to work.

jsonDict = {"One": 5, "Two": 6}
jsonEncoded = system.util.jsonEncode(jsonDict)
x = system.db.runPrepUpdate("UPDATE config SET configvalue = ? WHERE id = ?", [jsonEncoded, 2])

Now to see if I can get it back out!

I'm surprised. Question-mark placeholders (and colon-delimited placeholders in named queries) should never be quoted.

You are correct. I pasted it in before I finished the debug. I fixed the earlier post.
Thanks again, Phil.