diff --git a/lib/tsc.js b/lib/tsc.js
index 54e563e80cef4..29eed460b7e69 100644
--- a/lib/tsc.js
+++ b/lib/tsc.js
@@ -60,7 +60,7 @@ var __makeTemplateObject = (this && this.__makeTemplateObject) || function (cook
 var ts;
 (function (ts) {
     ts.versionMajorMinor = "3.4";
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     ts.emptyArray = [];
diff --git a/lib/tsserver.js b/lib/tsserver.js
index 81e0cb7e64c57..5ec760d252c66 100644
--- a/lib/tsserver.js
+++ b/lib/tsserver.js
@@ -85,7 +85,7 @@ var ts;
     // If changing the text in this section, be sure to test `configureNightly` too.
     ts.versionMajorMinor = "3.4";
     /** The version of the TypeScript compiler release */
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     /* @internal */
@@ -123104,6 +123104,11 @@ var ts;
              * typingsInstaller will run the command with `${npmLocation} install ...`.
              */
             Arguments.NpmLocation = "--npmLocation";
+            /**
+             * Flag indicating that the typings installer should try to validate the default npm location.
+             * If the default npm is not found when this flag is enabled, fallback to `npm install`
+             */
+            Arguments.ValidateDefaultNpmLocation = "--validateDefaultNpmLocation";
         })(Arguments = server.Arguments || (server.Arguments = {}));
         function hasArgument(argumentName) {
             return ts.sys.args.indexOf(argumentName) >= 0;
@@ -131462,7 +131467,7 @@ var ts;
             return Logger;
         }());
         var NodeTypingsInstaller = /** @class */ (function () {
-            function NodeTypingsInstaller(telemetryEnabled, logger, host, globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, event) {
+            function NodeTypingsInstaller(telemetryEnabled, logger, host, globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, validateDefaultNpmLocation, event) {
                 this.telemetryEnabled = telemetryEnabled;
                 this.logger = logger;
                 this.host = host;
@@ -131470,6 +131475,7 @@ var ts;
                 this.typingSafeListLocation = typingSafeListLocation;
                 this.typesMapLocation = typesMapLocation;
                 this.npmLocation = npmLocation;
+                this.validateDefaultNpmLocation = validateDefaultNpmLocation;
                 this.event = event;
                 this.activeRequestCount = 0;
                 this.requestQueue = [];
@@ -131526,6 +131532,9 @@ var ts;
                 if (this.npmLocation) {
                     args.push(server.Arguments.NpmLocation, this.npmLocation);
                 }
+                if (this.validateDefaultNpmLocation) {
+                    args.push(server.Arguments.ValidateDefaultNpmLocation);
+                }
                 var execArgv = [];
                 for (var _i = 0, _a = process.execArgv; _i < _a.length; _i++) {
                     var arg = _a[_i];
@@ -131710,7 +131719,7 @@ var ts;
                 var host = sys;
                 var typingsInstaller = disableAutomaticTypingAcquisition
                     ? undefined
-                    : new NodeTypingsInstaller(telemetryEnabled, logger, host, getGlobalTypingsCacheLocation(), typingSafeListLocation, typesMapLocation, npmLocation, event);
+                    : new NodeTypingsInstaller(telemetryEnabled, logger, host, getGlobalTypingsCacheLocation(), typingSafeListLocation, typesMapLocation, npmLocation, validateDefaultNpmLocation, event);
                 _this = _super.call(this, {
                     host: host,
                     cancellationToken: cancellationToken,
@@ -132105,6 +132114,7 @@ var ts;
         var typingSafeListLocation = server.findArgument(server.Arguments.TypingSafeListLocation); // TODO: GH#18217
         var typesMapLocation = server.findArgument(server.Arguments.TypesMapLocation) || ts.combinePaths(ts.getDirectoryPath(sys.getExecutingFilePath()), "typesMap.json");
         var npmLocation = server.findArgument(server.Arguments.NpmLocation);
+        var validateDefaultNpmLocation = server.hasArgument(server.Arguments.ValidateDefaultNpmLocation);
         function parseStringArray(argName) {
             var arg = server.findArgument(argName);
             if (arg === undefined) {
diff --git a/lib/tsserverlibrary.js b/lib/tsserverlibrary.js
index 54c3e4a50d18c..0b0f811167e24 100644
--- a/lib/tsserverlibrary.js
+++ b/lib/tsserverlibrary.js
@@ -84,7 +84,7 @@ var ts;
     // If changing the text in this section, be sure to test `configureNightly` too.
     ts.versionMajorMinor = "3.4";
     /** The version of the TypeScript compiler release */
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     /* @internal */
@@ -94853,6 +94853,11 @@ var ts;
              * typingsInstaller will run the command with `${npmLocation} install ...`.
              */
             Arguments.NpmLocation = "--npmLocation";
+            /**
+             * Flag indicating that the typings installer should try to validate the default npm location.
+             * If the default npm is not found when this flag is enabled, fallback to `npm install`
+             */
+            Arguments.ValidateDefaultNpmLocation = "--validateDefaultNpmLocation";
         })(Arguments = server.Arguments || (server.Arguments = {}));
         function hasArgument(argumentName) {
             return ts.sys.args.indexOf(argumentName) >= 0;
diff --git a/lib/typescript.js b/lib/typescript.js
index 1e462e6044707..8a87b339a32f5 100644
--- a/lib/typescript.js
+++ b/lib/typescript.js
@@ -75,7 +75,7 @@ var ts;
     // If changing the text in this section, be sure to test `configureNightly` too.
     ts.versionMajorMinor = "3.4";
     /** The version of the TypeScript compiler release */
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     /* @internal */
@@ -94844,6 +94844,11 @@ var ts;
              * typingsInstaller will run the command with `${npmLocation} install ...`.
              */
             Arguments.NpmLocation = "--npmLocation";
+            /**
+             * Flag indicating that the typings installer should try to validate the default npm location.
+             * If the default npm is not found when this flag is enabled, fallback to `npm install`
+             */
+            Arguments.ValidateDefaultNpmLocation = "--validateDefaultNpmLocation";
         })(Arguments = server.Arguments || (server.Arguments = {}));
         function hasArgument(argumentName) {
             return ts.sys.args.indexOf(argumentName) >= 0;
diff --git a/lib/typescriptServices.js b/lib/typescriptServices.js
index 696cb60201252..fc0ce0febb7b5 100644
--- a/lib/typescriptServices.js
+++ b/lib/typescriptServices.js
@@ -75,7 +75,7 @@ var ts;
     // If changing the text in this section, be sure to test `configureNightly` too.
     ts.versionMajorMinor = "3.4";
     /** The version of the TypeScript compiler release */
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     /* @internal */
@@ -94844,6 +94844,11 @@ var ts;
              * typingsInstaller will run the command with `${npmLocation} install ...`.
              */
             Arguments.NpmLocation = "--npmLocation";
+            /**
+             * Flag indicating that the typings installer should try to validate the default npm location.
+             * If the default npm is not found when this flag is enabled, fallback to `npm install`
+             */
+            Arguments.ValidateDefaultNpmLocation = "--validateDefaultNpmLocation";
         })(Arguments = server.Arguments || (server.Arguments = {}));
         function hasArgument(argumentName) {
             return ts.sys.args.indexOf(argumentName) >= 0;
diff --git a/lib/typingsInstaller.js b/lib/typingsInstaller.js
index 779668a162ae1..d5a364f4604ec 100644
--- a/lib/typingsInstaller.js
+++ b/lib/typingsInstaller.js
@@ -76,7 +76,7 @@ var ts;
     // If changing the text in this section, be sure to test `configureNightly` too.
     ts.versionMajorMinor = "3.4";
     /** The version of the TypeScript compiler release */
-    ts.version = ts.versionMajorMinor + ".4";
+    ts.version = ts.versionMajorMinor + ".5";
 })(ts || (ts = {}));
 (function (ts) {
     /* @internal */
@@ -94845,6 +94845,11 @@ var ts;
              * typingsInstaller will run the command with `${npmLocation} install ...`.
              */
             Arguments.NpmLocation = "--npmLocation";
+            /**
+             * Flag indicating that the typings installer should try to validate the default npm location.
+             * If the default npm is not found when this flag is enabled, fallback to `npm install`
+             */
+            Arguments.ValidateDefaultNpmLocation = "--validateDefaultNpmLocation";
         })(Arguments = server.Arguments || (server.Arguments = {}));
         function hasArgument(argumentName) {
             return ts.sys.args.indexOf(argumentName) >= 0;
@@ -95663,13 +95668,17 @@ var ts;
                 }
                 return FileLog;
             }());
-            function getDefaultNPMLocation(processName) {
+            function getDefaultNPMLocation(processName, validateDefaultNpmLocation, host) {
                 if (path.basename(processName).indexOf("node") === 0) {
-                    return "\"" + path.join(path.dirname(process.argv[0]), "npm") + "\"";
-                }
-                else {
-                    return "npm";
+                    var npmPath = path.join(path.dirname(process.argv[0]), "npm");
+                    if (!validateDefaultNpmLocation) {
+                        return npmPath;
+                    }
+                    if (host.fileExists(npmPath)) {
+                        return "\"" + npmPath + "\"";
+                    }
                 }
+                return "npm";
             }
             function loadTypesRegistryFile(typesRegistryFilePath, host, log) {
                 if (!host.fileExists(typesRegistryFilePath)) {
@@ -95695,15 +95704,16 @@ var ts;
             }
             var NodeTypingsInstaller = (function (_super) {
                 __extends(NodeTypingsInstaller, _super);
-                function NodeTypingsInstaller(globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, throttleLimit, log) {
+                function NodeTypingsInstaller(globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, validateDefaultNpmLocation, throttleLimit, log) {
                     var _this = _super.call(this, ts.sys, globalTypingsCacheLocation, typingSafeListLocation ? ts.toPath(typingSafeListLocation, "", ts.createGetCanonicalFileName(ts.sys.useCaseSensitiveFileNames)) : ts.toPath("typingSafeList.json", __dirname, ts.createGetCanonicalFileName(ts.sys.useCaseSensitiveFileNames)), typesMapLocation ? ts.toPath(typesMapLocation, "", ts.createGetCanonicalFileName(ts.sys.useCaseSensitiveFileNames)) : ts.toPath("typesMap.json", __dirname, ts.createGetCanonicalFileName(ts.sys.useCaseSensitiveFileNames)), throttleLimit, log) || this;
-                    _this.npmPath = npmLocation !== undefined ? npmLocation : getDefaultNPMLocation(process.argv[0]);
+                    _this.npmPath = npmLocation !== undefined ? npmLocation : getDefaultNPMLocation(process.argv[0], validateDefaultNpmLocation, _this.installTypingHost);
                     if (ts.stringContains(_this.npmPath, " ") && _this.npmPath[0] !== "\"") {
                         _this.npmPath = "\"" + _this.npmPath + "\"";
                     }
                     if (_this.log.isEnabled()) {
                         _this.log.writeLine("Process id: " + process.pid);
                         _this.log.writeLine("NPM location: " + _this.npmPath + " (explicit '" + server.Arguments.NpmLocation + "' " + (npmLocation === undefined ? "not " : "") + " provided)");
+                        _this.log.writeLine("validateDefaultNpmLocation: " + validateDefaultNpmLocation);
                     }
                     (_this.nodeExecSync = require("child_process").execSync);
                     _this.ensurePackageDirectoryExists(globalTypingsCacheLocation);
@@ -95830,6 +95840,7 @@ var ts;
             var typingSafeListLocation = server.findArgument(server.Arguments.TypingSafeListLocation);
             var typesMapLocation = server.findArgument(server.Arguments.TypesMapLocation);
             var npmLocation = server.findArgument(server.Arguments.NpmLocation);
+            var validateDefaultNpmLocation = server.hasArgument(server.Arguments.ValidateDefaultNpmLocation);
             var log = new FileLog(logFilePath);
             if (log.isEnabled()) {
                 process.on("uncaughtException", function (e) {
@@ -95842,7 +95853,7 @@ var ts;
                 }
                 process.exit(0);
             });
-            var installer = new NodeTypingsInstaller(globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, 5, log);
+            var installer = new NodeTypingsInstaller(globalTypingsCacheLocation, typingSafeListLocation, typesMapLocation, npmLocation, validateDefaultNpmLocation, 5, log);
             installer.listen();
             function indent(newline, str) {
                 return newline + "    " + str.replace(/\r?\n/, newline + "    ");