diff --git a/localtypings/pxtarget.d.ts b/localtypings/pxtarget.d.ts
index 6e91644dbf4d..ee4495e1a508 100644
--- a/localtypings/pxtarget.d.ts
+++ b/localtypings/pxtarget.d.ts
@@ -738,6 +738,7 @@ declare namespace ts.pxtc {
         flashChecksumAddr?: number;
         ramSize?: number;
         patches?: pxt.Map<UpgradePolicy[]>; // semver range -> upgrade policies
+        pyPatches?: pxt.Map<UpgradePolicy[]>; // semver range -> upgrade policies
         openocdScript?: string;
         uf2Family?: string;
         onStartText?: boolean;
diff --git a/pxtcompiler/simpledriver.ts b/pxtcompiler/simpledriver.ts
index 8b7aef04fd70..c7a3809d274f 100644
--- a/pxtcompiler/simpledriver.ts
+++ b/pxtcompiler/simpledriver.ts
@@ -172,6 +172,9 @@ namespace pxt {
                 return mainPkg.getCompileOptionsAsync(target)
             }).then(opts => {
                 patchTS(mainPkg.targetVersion(), opts)
+                if (mainPkg.getPreferredEditor() === pxt.PYTHON_PROJECT_NAME) {
+                    patchPY(mainPkg.targetVersion(), opts)
+                }
                 prepPythonOptions(opts)
                 return opts
             })
@@ -209,6 +212,22 @@ namespace pxt {
         }
     }
 
+    export function patchPY(version: string, opts: pxtc.CompileOptions) {
+        if (!version)
+            return
+        pxt.debug(`applying PY patches relative to ${version}`)
+        for (let fn of Object.keys(opts.fileSystem)) {
+            if (fn.indexOf("/") == -1 && U.endsWith(fn, ".py")) {
+                const initial = opts.fileSystem[fn]
+                const patched = pxt.patching.patchPython(version, initial)
+                if (initial != patched) {
+                    pxt.debug(`applying PY patch to ${fn}`)
+                    opts.fileSystem[fn] = patched
+                }
+            }
+        }
+    }
+
     // eslint-disable-next-line no-var
     declare var global: any;
     // eslint-disable-next-line no-var
diff --git a/pxtlib/patch.ts b/pxtlib/patch.ts
index 1fb6b426bfa6..99b22b7b3b3d 100644
--- a/pxtlib/patch.ts
+++ b/pxtlib/patch.ts
@@ -2,6 +2,16 @@ namespace pxt.patching {
     export function computePatches(version: string, kind?: string): ts.pxtc.UpgradePolicy[] {
         const patches = pxt.appTarget.compile ? pxt.appTarget.compile.patches : undefined;
         if (!patches) return undefined;
+        return parsePatches(version, patches, kind);
+    }
+
+    export function computePyPatches(version: string, kind?: string): ts.pxtc.UpgradePolicy[] {
+        const patches = pxt.appTarget.compile ? pxt.appTarget.compile.pyPatches : undefined;
+        if (!patches) return undefined;
+        return parsePatches(version, patches, kind);
+    }
+
+    function parsePatches(version: string, patches: Map<ts.pxtc.UpgradePolicy[]>, kind?: string): ts.pxtc.UpgradePolicy[] {
         const v = pxt.semver.tryParse(version || "0.0.0") || pxt.semver.tryParse("0.0.0");
         let r: ts.pxtc.UpgradePolicy[] = [];
         Object.keys(patches)
@@ -30,6 +40,15 @@ namespace pxt.patching {
 
     export function patchJavaScript(pkgTargetVersion: string, fileContents: string): string {
         const upgrades = pxt.patching.computePatches(pkgTargetVersion);
+        return patchTextCode(pkgTargetVersion, fileContents, upgrades);
+    }
+
+    export function patchPython(pkgTargetVersion: string, fileContents: string): string {
+        const upgrades = pxt.patching.computePyPatches(pkgTargetVersion);
+        return patchTextCode(pkgTargetVersion, fileContents, upgrades);
+    }
+
+    function patchTextCode(pkgTargetVersion: string, fileContents: string, upgrades: pxtc.UpgradePolicy[]): string {
         let updatedContents = fileContents;
         if (upgrades) {
             upgrades.filter(u => u.type === "api").forEach(rule => {
diff --git a/webapp/src/compiler.ts b/webapp/src/compiler.ts
index 17c96264fac0..ac06e0b0de62 100644
--- a/webapp/src/compiler.ts
+++ b/webapp/src/compiler.ts
@@ -835,7 +835,12 @@ export function applyUpgradesAsync(): Promise<UpgradeResult> {
         });
     }
 
-    const upgradeOp = epkg.header.editor !== pxt.BLOCKS_PROJECT_NAME ? upgradeFromTSAsync : upgradeFromBlocksAsync;
+    const upgradeOp =
+      epkg.header.editor !== pxt.BLOCKS_PROJECT_NAME
+        ? epkg.header.editor !== pxt.PYTHON_PROJECT_NAME
+          ? upgradeFromTSAsync
+          : upgradeFromPythonAsync
+        : upgradeFromBlocksAsync;
 
     let projectNeverCompiled = false;
 
@@ -922,7 +927,7 @@ function upgradeFromBlocksAsync(): Promise<UpgradeResult> {
         });
 }
 
-function upgradeFromTSAsync(): Promise<UpgradeResult> {
+async function upgradeFromTSAsync(): Promise<UpgradeResult> {
     const mainPkg = pkg.mainPkg;
     const project = pkg.getEditorPkg(mainPkg);
     const targetVersion = project.header.targetVersion;
@@ -937,20 +942,49 @@ function upgradeFromTSAsync(): Promise<UpgradeResult> {
 
     pxt.debug("Applying upgrades to TypeScript")
 
-    return checkPatchAsync(patchedFiles)
-        .then(() => {
-            return {
-                success: true,
-                editor: pxt.JAVASCRIPT_PROJECT_NAME,
-                patchedFiles
-            };
-        })
-        .catch(e => {
-            return {
-                success: false,
-                errorCodes: e.errorCodes
-            };
-        });
+    try {
+        await checkPatchAsync(patchedFiles)
+        return {
+            success: true,
+            editor: pxt.JAVASCRIPT_PROJECT_NAME,
+            patchedFiles
+        };
+    } catch (e) {
+        return {
+            success: false,
+            errorCodes: e.errorCodes
+        };
+    };
+}
+
+async function upgradeFromPythonAsync(): Promise<UpgradeResult> {
+    const mainPkg = pkg.mainPkg;
+    const project = pkg.getEditorPkg(mainPkg);
+    const targetVersion = project.header.targetVersion;
+
+    const patchedFiles: pxt.Map<string> = {};
+    pxt.Util.values(project.files).filter(isPyFile).forEach(file => {
+        const patched = pxt.patching.patchPython(targetVersion, file.content);
+        if (patched != file.content) {
+            patchedFiles[file.name] = patched;
+        }
+    });
+
+    pxt.debug("Applying upgrades to Python")
+
+    try {
+        await checkPatchAsync(patchedFiles);
+        return {
+            success: true,
+            editor: pxt.PYTHON_PROJECT_NAME,
+            patchedFiles
+        };
+    } catch (e) {
+        return {
+            success: false,
+            errorCodes: e.errorCodes
+        };
+    }
 }
 
 interface UpgradeError extends Error {
@@ -1000,6 +1034,10 @@ function isTsFile(file: pkg.File) {
     return pxt.Util.endsWith(file.getName(), ".ts");
 }
 
+function isPyFile(file: pkg.File) {
+    return pxt.Util.endsWith(file.getName(), ".py");
+}
+
 export function updatePackagesAsync(packages: pkg.EditorPackage[], token?: pxt.Util.CancellationToken): Promise<boolean> {
     const epkg = pkg.mainEditorPkg();
     let backup: pxt.workspace.Header;