diff --git a/extensions/ql-vscode/src/databases/database-fetcher.ts b/extensions/ql-vscode/src/databases/database-fetcher.ts
index 995786dffa0..13f64e4f7fe 100644
--- a/extensions/ql-vscode/src/databases/database-fetcher.ts
+++ b/extensions/ql-vscode/src/databases/database-fetcher.ts
@@ -666,7 +666,9 @@ function isFile(databaseUrl: string) {
  *
  * @param databasePath The full path to the unzipped database
  */
-async function ensureZippedSourceLocation(databasePath: string): Promise<void> {
+export async function ensureZippedSourceLocation(
+  databasePath: string,
+): Promise<void> {
   const srcFolderPath = join(databasePath, "src");
   const srcZipPath = `${srcFolderPath}.zip`;
 
diff --git a/extensions/ql-vscode/src/databases/local-databases-ui.ts b/extensions/ql-vscode/src/databases/local-databases-ui.ts
index 81edbda186e..3b6f8127162 100644
--- a/extensions/ql-vscode/src/databases/local-databases-ui.ts
+++ b/extensions/ql-vscode/src/databases/local-databases-ui.ts
@@ -995,14 +995,15 @@ export class DatabaseUI extends DisposableObject {
       return undefined;
     }
 
-    if (byFolder) {
+    if (byFolder && !uri.fsPath.endsWith("testproj")) {
       const fixedUri = await this.fixDbUri(uri);
       // we are selecting a database folder
       return await this.databaseManager.openDatabase(fixedUri, {
         type: "folder",
       });
     } else {
-      // we are selecting a database archive. Must unzip into a workspace-controlled area
+      // we are selecting a database archive or a testproj.
+      // Unzip archives (if an archive) and copy into a workspace-controlled area
       // before importing.
       return await importLocalDatabase(
         this.app.commands,
diff --git a/extensions/ql-vscode/src/databases/local-databases/database-manager.ts b/extensions/ql-vscode/src/databases/local-databases/database-manager.ts
index a1a7dc28be4..f512e5f5df8 100644
--- a/extensions/ql-vscode/src/databases/local-databases/database-manager.ts
+++ b/extensions/ql-vscode/src/databases/local-databases/database-manager.ts
@@ -43,6 +43,7 @@ import { DatabaseResolver } from "./database-resolver";
 import { telemetryListener } from "../../common/vscode/telemetry";
 import type { LanguageContextStore } from "../../language-context-store";
 import type { DatabaseOrigin } from "./database-origin";
+import { ensureZippedSourceLocation } from "../database-fetcher";
 
 /**
  * The name of the key in the workspaceState dictionary in which we
@@ -227,8 +228,16 @@ export class DatabaseManager extends DisposableObject {
       "codeql-database.yml",
     );
 
+    let originStat;
+    try {
+      originStat = await stat(originDbYml);
+    } catch (e) {
+      // if there is an error here, assume that the origin database
+      // is no longer available. Safely ignore and do not try to re-import.
+      return false;
+    }
+
     try {
-      const originStat = await stat(originDbYml);
       const importedStat = await stat(importedDbYml);
       return originStat.mtimeMs > importedStat.mtimeMs;
     } catch (e) {
@@ -252,6 +261,7 @@ export class DatabaseManager extends DisposableObject {
 
     await this.removeDatabaseItem(dbItem);
     await copy(dbItem.origin.path, databaseUri.fsPath);
+    await ensureZippedSourceLocation(databaseUri.fsPath);
     const newDbItem = new DatabaseItemImpl(databaseUri, dbItem.contents, {
       dateAdded: Date.now(),
       language: dbItem.language,