diff --git a/src/vs/workbench/services/editor/browser/editorOverrideService.ts b/src/vs/workbench/services/editor/browser/editorOverrideService.ts
index d0eec2dba448b21648c68abe9b87875f73f23c7c..5d87f892e2a6e3ca8686dd371bdfc4e0061fe292 100644
--- a/src/vs/workbench/services/editor/browser/editorOverrideService.ts
+++ b/src/vs/workbench/services/editor/browser/editorOverrideService.ts
@@ -22,6 +22,8 @@ import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
 import { registerSingleton } from 'vs/platform/instantiation/common/extensions';
 import { IStorageService, StorageScope, StorageTarget } from 'vs/platform/storage/common/storage';
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
+import { IHostService } from 'vs/workbench/services/host/browser/host';
+import { ILogService } from 'vs/platform/log/common/log';
 
 interface IContributedEditorInput extends IEditorInput {
 	viewType?: string;
@@ -56,7 +58,9 @@ export class EditorOverrideService extends Disposable implements IEditorOverride
 		@INotificationService private readonly notificationService: INotificationService,
 		@ITelemetryService private readonly telemetryService: ITelemetryService,
 		@IStorageService private readonly storageService: IStorageService,
-		@IExtensionService private readonly extensionService: IExtensionService
+		@IExtensionService private readonly extensionService: IExtensionService,
+		@IHostService private readonly hostService: IHostService,
+		@ILogService private readonly logService: ILogService,
 	) {
 		super();
 		// Read in the cache on statup
@@ -75,8 +79,10 @@ export class EditorOverrideService extends Disposable implements IEditorOverride
 		});
 
 		// When the setting changes we want to ensure that it is properly converted
-		this._register(this.configurationService.onDidChangeConfiguration(() => {
-			this.convertOldAssociationFormat();
+		this._register(this.configurationService.onDidChangeConfiguration((e) => {
+			if (e.affectsConfiguration(editorsAssociationsSettingId)) {
+				this.convertOldAssociationFormat();
+			}
 		}));
 	}
 
@@ -177,23 +183,42 @@ export class EditorOverrideService extends Disposable implements IEditorOverride
 	}
 
 	private convertOldAssociationFormat(): void {
-		const rawAssociations = this.configurationService.getValue<EditorAssociations | { [fileNamePattern: string]: string }>(editorsAssociationsSettingId) || [];
-		// If it's not an array, then it's the new format
-		if (!Array.isArray(rawAssociations)) {
-			return;
-		}
-		let newSettingObject = Object.create(null);
-		// Make the correctly formatted object from the array and then set that object
-		for (const association of rawAssociations) {
-			if (association.filenamePattern) {
-				newSettingObject[association.filenamePattern] = association.viewType;
+		this.hostService.hadLastFocus().then(hadLastFocus => {
+			if (!hadLastFocus) {
+				return;
 			}
-		}
-		this.configurationService.updateValue(editorsAssociationsSettingId, newSettingObject);
+			const rawAssociations = this.configurationService.getValue<EditorAssociations | { [fileNamePattern: string]: string }>(editorsAssociationsSettingId) || {};
+			// If it's not an array, then it's the new format
+			if (!Array.isArray(rawAssociations)) {
+				return;
+			}
+			let newSettingObject = Object.create(null);
+			// Make the correctly formatted object from the array and then set that object
+			for (const association of rawAssociations) {
+				if (association.filenamePattern) {
+					newSettingObject[association.filenamePattern] = association.viewType;
+				}
+			}
+			this.logService.info(`Migrating ${editorsAssociationsSettingId}`);
+			this.configurationService.updateValue(editorsAssociationsSettingId, newSettingObject);
+		});
 	}
 
 	private getAllUserAssociations(): EditorAssociations {
-		const rawAssociations = this.configurationService.getValue<{ [fileNamePattern: string]: string }>(editorsAssociationsSettingId) || [];
+		let rawAssociations = this.configurationService.getValue<EditorAssociations | { [fileNamePattern: string]: string }>(editorsAssociationsSettingId) || {};
+
+		// If it's an array then it is old format
+		if (Array.isArray(rawAssociations)) {
+			// Make the correctly formatted object
+			const newValue = Object.create(null);
+			for (const association of rawAssociations) {
+				if (association.filenamePattern) {
+					newValue[association.filenamePattern] = association.viewType;
+				}
+			}
+			rawAssociations = newValue;
+		}
+
 		let associations = [];
 		for (const [key, value] of Object.entries(rawAssociations)) {
 			const association: EditorAssociation = {