diff --git a/docs/release-notes.md b/docs/release-notes.md
index 2e1e050e..2ff4ec0a 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -10,6 +10,7 @@
 ## Upcoming release
 * For players:
   * Fixed rare error when a mod adds/removes event handlers asynchronously.
+  * Removed the experimental `RewriteInParallel` option added in SMAPI 3.6 (it was already disabled by default). Unfortunately this caused intermittent unpredictable errors when enabled.
 
 * For modders:
   * You can now read/write `SDate` values to JSON (e.g. for `config.json`, network mod messages, etc).
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
index f8c901e0..dbb5f696 100644
--- a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
+++ b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
@@ -76,10 +76,9 @@ namespace StardewModdingAPI.Framework.ModLoading
         /// <param name="mod">The mod for which the assembly is being loaded.</param>
         /// <param name="assemblyPath">The assembly file path.</param>
         /// <param name="assumeCompatible">Assume the mod is compatible, even if incompatible code is detected.</param>
-        /// <param name="rewriteInParallel">Whether to enable experimental parallel rewriting.</param>
         /// <returns>Returns the rewrite metadata for the preprocessed assembly.</returns>
         /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
-        public Assembly Load(IModMetadata mod, string assemblyPath, bool assumeCompatible, bool rewriteInParallel)
+        public Assembly Load(IModMetadata mod, string assemblyPath, bool assumeCompatible)
         {
             // get referenced local assemblies
             AssemblyParseResult[] assemblies;
@@ -109,7 +108,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                     continue;
 
                 // rewrite assembly
-                bool changed = this.RewriteAssembly(mod, assembly.Definition, loggedMessages, logPrefix: "      ", rewriteInParallel);
+                bool changed = this.RewriteAssembly(mod, assembly.Definition, loggedMessages, logPrefix: "      ");
 
                 // detect broken assembly reference
                 foreach (AssemblyNameReference reference in assembly.Definition.MainModule.AssemblyReferences)
@@ -263,10 +262,9 @@ namespace StardewModdingAPI.Framework.ModLoading
         /// <param name="assembly">The assembly to rewrite.</param>
         /// <param name="loggedMessages">The messages that have already been logged for this mod.</param>
         /// <param name="logPrefix">A string to prefix to log messages.</param>
-        /// <param name="rewriteInParallel">Whether to enable experimental parallel rewriting.</param>
         /// <returns>Returns whether the assembly was modified.</returns>
         /// <exception cref="IncompatibleInstructionException">An incompatible CIL instruction was found while rewriting the assembly.</exception>
-        private bool RewriteAssembly(IModMetadata mod, AssemblyDefinition assembly, HashSet<string> loggedMessages, string logPrefix, bool rewriteInParallel)
+        private bool RewriteAssembly(IModMetadata mod, AssemblyDefinition assembly, HashSet<string> loggedMessages, string logPrefix)
         {
             ModuleDefinition module = assembly.MainModule;
             string filename = $"{assembly.Name.Name}.dll";
@@ -315,7 +313,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                     return rewritten;
                 }
             );
-            bool anyRewritten = rewriter.RewriteModule(rewriteInParallel);
+            bool anyRewritten = rewriter.RewriteModule();
 
             // handle rewrite flags
             foreach (IInstructionHandler handler in handlers)
diff --git a/src/SMAPI/Framework/ModLoading/Framework/RecursiveRewriter.cs b/src/SMAPI/Framework/ModLoading/Framework/RecursiveRewriter.cs
index 34c78c7d..fb651465 100644
--- a/src/SMAPI/Framework/ModLoading/Framework/RecursiveRewriter.cs
+++ b/src/SMAPI/Framework/ModLoading/Framework/RecursiveRewriter.cs
@@ -1,8 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
 using Mono.Collections.Generic;
@@ -57,59 +55,24 @@ namespace StardewModdingAPI.Framework.ModLoading.Framework
         }
 
         /// <summary>Rewrite the loaded module code.</summary>
-        /// <param name="rewriteInParallel">Whether to enable experimental parallel rewriting.</param>
         /// <returns>Returns whether the module was modified.</returns>
-        public bool RewriteModule(bool rewriteInParallel)
+        public bool RewriteModule()
         {
             IEnumerable<TypeDefinition> types = this.Module.GetTypes().Where(type => type.BaseType != null); // skip special types like <Module>
 
-            // experimental parallel rewriting
-            // This may cause intermittent startup errors and is disabled by default: https://github.com/Pathoschild/SMAPI/issues/721
-            if (rewriteInParallel)
+            bool changed = false;
+
+            try
             {
-                int typesChanged = 0;
-                Exception exception = null;
-
-                Parallel.ForEach(types, type =>
-                {
-                    if (exception != null)
-                        return;
-
-                    bool changed = false;
-                    try
-                    {
-                        changed = this.RewriteTypeDefinition(type);
-                    }
-                    catch (Exception ex)
-                    {
-                        exception ??= ex;
-                    }
-
-                    if (changed)
-                        Interlocked.Increment(ref typesChanged);
-                });
-
-                return exception == null
-                    ? typesChanged > 0
-                    : throw new Exception($"Rewriting {this.Module.Name} failed.", exception);
+                foreach (var type in types)
+                    changed |= this.RewriteTypeDefinition(type);
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Rewriting {this.Module.Name} failed.", ex);
             }
 
-            // non-parallel rewriting
-            {
-                bool changed = false;
-
-                try
-                {
-                    foreach (var type in types)
-                        changed |= this.RewriteTypeDefinition(type);
-                }
-                catch (Exception ex)
-                {
-                    throw new Exception($"Rewriting {this.Module.Name} failed.", ex);
-                }
-
-                return changed;
-            }
+            return changed;
         }
 
 
diff --git a/src/SMAPI/Framework/Models/SConfig.cs b/src/SMAPI/Framework/Models/SConfig.cs
index 1c682f96..3a3f6960 100644
--- a/src/SMAPI/Framework/Models/SConfig.cs
+++ b/src/SMAPI/Framework/Models/SConfig.cs
@@ -16,7 +16,6 @@ namespace StardewModdingAPI.Framework.Models
         {
             [nameof(CheckForUpdates)] = true,
             [nameof(ParanoidWarnings)] = Constants.IsDebugBuild,
-            [nameof(RewriteInParallel)] = Constants.IsDebugBuild,
             [nameof(UseBetaChannel)] = Constants.ApiVersion.IsPrerelease(),
             [nameof(GitHubProjectName)] = "Pathoschild/SMAPI",
             [nameof(WebApiBaseUrl)] = "https://smapi.io/api/",
@@ -41,9 +40,6 @@ namespace StardewModdingAPI.Framework.Models
         /// <summary>Whether to check for newer versions of SMAPI and mods on startup.</summary>
         public bool CheckForUpdates { get; set; }
 
-        /// <summary>Whether to enable experimental parallel rewriting.</summary>
-        public bool RewriteInParallel { get; set; } = (bool)SConfig.DefaultValues[nameof(SConfig.RewriteInParallel)];
-
         /// <summary>Whether to add a section to the 'mod issues' list for mods which which directly use potentially sensitive .NET APIs like file or shell access.</summary>
         public bool ParanoidWarnings { get; set; } = (bool)SConfig.DefaultValues[nameof(SConfig.ParanoidWarnings)];
 
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index 72ef9095..fd8d7034 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -337,8 +337,6 @@ namespace StardewModdingAPI.Framework
             // add headers
             if (this.Settings.DeveloperMode)
                 this.Monitor.Log($"You have SMAPI for developers, so the console will be much more verbose. You can disable developer mode by installing the non-developer version of SMAPI, or by editing {Constants.ApiConfigPath}.", LogLevel.Info);
-            if (this.Settings.RewriteInParallel)
-                this.Monitor.Log($"You enabled experimental parallel rewriting. This may result in faster startup times, but intermittent startup errors. You can disable it by reinstalling SMAPI or editing {Constants.ApiConfigPath}.", LogLevel.Info);
             if (!this.Settings.CheckForUpdates)
                 this.Monitor.Log($"You configured SMAPI to not check for updates. Running an old version of SMAPI is not recommended. You can enable update checks by reinstalling SMAPI or editing {Constants.ApiConfigPath}.", LogLevel.Warn);
             if (!this.Monitor.WriteToConsole)
@@ -983,7 +981,7 @@ namespace StardewModdingAPI.Framework
                 Assembly modAssembly;
                 try
                 {
-                    modAssembly = assemblyLoader.Load(mod, assemblyPath, assumeCompatible: mod.DataRecord?.Status == ModStatus.AssumeCompatible, rewriteInParallel: this.Settings.RewriteInParallel);
+                    modAssembly = assemblyLoader.Load(mod, assemblyPath, assumeCompatible: mod.DataRecord?.Status == ModStatus.AssumeCompatible);
                     this.ModRegistry.TrackAssemblies(mod, modAssembly);
                 }
                 catch (IncompatibleInstructionException) // details already in trace logs
diff --git a/src/SMAPI/SMAPI.config.json b/src/SMAPI/SMAPI.config.json
index 0a6d8372..6ba64fe7 100644
--- a/src/SMAPI/SMAPI.config.json
+++ b/src/SMAPI/SMAPI.config.json
@@ -33,15 +33,6 @@ copy all the settings, or you may cause bugs due to overridden changes in future
      */
     "DeveloperMode": true,
 
-    /**
-     * Whether to enable experimental parallel rewriting when SMAPI is loading mods. This can
-     * reduce startup time when you have many mods installed, but is experimental and may cause
-     * intermittent startup errors.
-     *
-     * When this is commented out, it'll be true for local debug builds and false otherwise.
-     */
-    //"RewriteInParallel": false,
-
     /**
      * Whether to add a section to the 'mod issues' list for mods which directly use potentially
      * sensitive .NET APIs like file or shell access. Note that many mods do this legitimately as