How to Clear Outlook Cache in Windows 11 (2026)

To clear Outlook cache in Windows 11, use the steps built into your version of Outlook: in the new Outlook for Windows, go to Settings > General > Storage and choose to empty the cached data; in classic Outlook, close the app and delete the contents of the RoamCache folder at %localappdata%\Microsoft\Outlook\RoamCache. Clearing the cache removes stored copies of emails, attachments, and settings, then forces Outlook to rebuild them from the server, which fixes most sync errors, stuck loading, and search problems — and it never deletes your emails, accounts, or rules.

If Outlook has been behaving strangely lately — refusing to sync, crashing on startup, showing outdated folders, or throwing cryptic errors like the pii_email series — a stale or corrupted cache is one of the most common culprits. This guide walks you through every reliable way to clear the Outlook cache in Windows 11, covering the new Outlook for Windows, classic Outlook, Outlook on the web, the autocomplete contact list, and the Windows credential store that can trap you in sign-in loops. Follow the method that matches your setup and you should be back to a working inbox within minutes.

What the Outlook cache is and why it causes problems

The Outlook cache is a local copy of your mailbox data stored on your Windows 11 PC. In classic Outlook this mainly lives in an offline storage (OST) file plus a RoamCache folder that holds user-specific settings, navigation pane customizations, and shared-folder metadata. The new Outlook for Windows stores its own cached mailbox data and local app data separately, while Outlook on the web keeps its cache in your browser as cookies, local storage, and service-worker data.

Caching exists for a good reason: it lets you read mail offline, makes search fast, and reduces load on the mail server. But the cache can quietly go bad. An interrupted sync, a crashed update, or a corrupted settings file can leave Outlook working from stale or damaged local data while the real mailbox on the server is perfectly fine. The symptoms are familiar: the app hangs on “Loading profile”, folders stop updating, search returns nothing, or you get strange error codes that no amount of restarting seems to fix.

That is why knowing how to clear the Outlook cache in Windows 11 is such a useful skill. You are not touching the server copy of your mailbox — you are simply deleting the local scratch copies and telling Outlook to download fresh ones. On a fast connection a rebuild takes anywhere from a few minutes to half an hour, and the payoff is often immediate: sync errors gone, search working again, and error dialogs like pii_email codes disappearing. Microsoft’s own guidance for Outlook sync and startup problems routinely starts with clearing local data, because it is low-risk and surprisingly effective.

Before you clear the Outlook cache in Windows 11, close Outlook fully and identify which version you are running. Open Outlook and look at the window title or the Settings gear icon — the “new Outlook” toggle in the top-right corner of classic Outlook also tells you which app is active. The methods below show every way to clear the Outlook cache in Windows 11, ordered from easiest to most hands-on, so start at the top.

Methods to clear the Outlook cache in Windows 11

Method 1: New Outlook for Windows — clear from Settings > General > Storage

The new Outlook for Windows includes a built-in button that empties its local cache without touching your mailbox. This is the quickest way to clear the Outlook cache in Windows 11 if you use the current default mail app.

Open the new Outlook for Windows on your Windows 11 PC.
Click the Settings gear icon in the top-right corner of the window.
In the Settings pane, select General, then click Storage.
Look for the Cached data section and click Empty or Clear (the exact wording depends on the app version).
Confirm the prompt. Outlook will delete its local cached files and restart.
Sign back in if asked, and let Outlook re-sync your mailbox. Leave the app open until the folders finish updating.

This targets the new app’s local storage only. Your accounts, folders, rules, and signatures all remain intact because they sync from your Microsoft account and mail server. If the app was stuck loading or showing outdated content, it rebuilds a clean cache and behaves normally again.

Method 2: Classic Outlook — delete the RoamCache folder

Classic Outlook (bundled with Microsoft 365 and Office) has no single “clear cache” button, so to clear the Outlook cache in Windows 11 for the classic app you work directly with its per-user settings cache, which lives in a folder you can safely empty. Deleting the contents of RoamCache resets navigation pane state and views to defaults and often resolves startup hangs and odd interface behavior.

Close classic Outlook completely. Check the system tray near the clock — if the Outlook icon is still there, right-click it and choose Close.
Press Windows key + R to open the Run dialog.
Type %localappdata%\Microsoft\Outlook\RoamCache and press Enter to open the folder in File Explorer.
Select all files inside (Ctrl + A) and delete them. Delete only the contents, not the RoamCache folder itself.
Empty the Recycle Bin, then reopen Outlook. It recreates the cache files from scratch, which takes a few minutes the first time.

For deeper problems — a corrupted offline mailbox, for example — go a step further and delete the OST file. Open Run, type %localappdata%\Microsoft\Outlook, and locate the .ost file matching your account. Deleting it forces Outlook to rebuild the entire offline copy of your mailbox. This is safe for IMAP, Exchange, and Microsoft 365 accounts because the master copy lives on the server, but never do this with a POP3 account unless you have a backup. Microsoft documents the repair process here: Repair Outlook data files (.pst and .ost).

Method 3: Outlook on the web — clear browser site data

If you use Outlook through the browser (outlook.office.com or outlook.live.com), clearing the Outlook cache in Windows 11 means clearing your browser’s site data, because the web app’s cache lives in the browser itself. Clearing site-specific data removes stored session information and cached assets that can freeze the web app, show a blank screen, or loop on sign-in.

Open your browser and go to outlook.office.com or outlook.live.com, whichever you use.
Click the lock or tune icon to the left of the address bar.
Select Cookies and site data (Chrome/Edge) or Clear cookies and site data (Firefox).
Use Manage on-device site data to delete the entries for outlook.office.com and outlook.live.com.
Close the tab, reopen the site, and sign in again.

This is the fastest way to clear the Outlook cache in Windows 11 for the web version, and it does not affect your other browser data, bookmarks, or saved passwords. See Microsoft’s official support hub for the latest Outlook on the web troubleshooting steps: Outlook help and support.

Method 4: Clear the autocomplete (suggested contacts) cache

The autocomplete list is a separate piece of the puzzle when you clear the Outlook cache in Windows 11: the suggested recipients that appear when you type in the To field can also go stale. A corrupt entry can make emails bounce or go to the wrong address.

In classic Outlook, start a new email and type the first few letters of the problematic contact in the To field.
Hover over the unwanted suggestion in the dropdown and click the X that appears, or select it and press Delete.
To wipe the entire list in classic Outlook: go to File > Options > Mail, scroll to Send messages, and click Empty Auto-Complete List.
In the new Outlook for Windows, hover over a suggested contact in the compose window and click the X to remove it.

Removing individual suggestions is usually enough, since corruption is typically limited to one or two entries. A full wipe is for cases where the whole suggestion list behaves erratically.

Method 5: Clear cached credentials via Credential Manager

Sometimes clearing the Outlook cache in Windows 11 is not enough: if Outlook keeps asking for your password in a loop, or refuses to connect right after you changed it, a stale credential stored by Windows may be the real problem. Clearing it forces a clean authentication.

Press Windows key + R, type control /name Microsoft.CredentialManager, and press Enter.
Select Windows Credentials.
Find entries starting with MicrosoftOffice, Outlook, or your email address.
Expand each one and click Remove.
Reopen Outlook, sign in with your current password, and complete any multi-factor authentication prompts.

This resolves the classic “Outlook keeps prompting for credentials” loop that survives password changes and restarts. It is also worth doing when Outlook throws connection errors right after a Microsoft 365 update. If you recently updated Office and started seeing the pii_email error family, clearing stale credentials alongside the cache is a sensible combination — see our guide on fixing the pii_email error after an Outlook update.

What clearing the cache does NOT delete

Many people hesitate to clear the Outlook cache in Windows 11 because they fear losing emails, so let me be explicit. The reality: clearing the cache is one of the safest maintenance tasks you can perform. Here is what stays untouched.

Your emails are safe. For Exchange, Microsoft 365, Outlook.com, Gmail, and any IMAP account, the master copy of every message lives on the mail server. Deleting the local cache just removes the copy on your PC; Outlook downloads fresh copies the next time it syncs. The only exception is a POP3 account configured to download and delete mail from the server — back up your PST file first in that case.

Your accounts, passwords, and profiles are safe. Clearing cached data does not remove your mail accounts or delete your profile. The new Outlook keeps your account list synced to your Microsoft account, and classic Outlook keeps profiles in the Windows registry and AppData — places these steps do not touch.

Your rules, signatures, and settings mostly survive. Server-side rules (Exchange/Microsoft 365) live on the server and are never at risk. What you may notice after clearing RoamCache in classic Outlook is that minor interface customizations — navigation pane ordering, custom views — reset to defaults. That is cosmetic and takes a minute to put back.

Your calendar, contacts, and tasks are safe. These sync from the server exactly like email and reappear as Outlook re-syncs. Just let Outlook complete one full sync first if you created anything offline that has not uploaded yet, so nothing pending is stranded.

When clearing the cache actually fixes things

Clearing the Outlook cache in Windows 11 is not magic, but it is the right first move for a specific family of problems. If your symptom is on this list, start here before trying anything more drastic.

pii_email errors. The pii_email family of Outlook error codes — including pii_email_e9d48ac2533bded18981 and its cousins — most often trace back to corrupted local data or conflicting cached state after an update. Clearing the cache, and where relevant the stale credentials described above, resolves a large share of these. See our dedicated guide on the pii_email_e9d48ac2533bded18981 error code.

Sync issues and folders not updating. If new mail arrives on your phone but not in Outlook on Windows 11, or sent items sit in the Outbox, a damaged OST or stale cache is the likely cause. Clearing it and forcing a fresh sync usually restores normal flow. Related reading: Outlook not receiving emails — how to fix it.

Stuck loading or crashing on startup. When Outlook freezes on “Loading profile” or crashes seconds after opening, corrupt RoamCache files or a damaged OST are prime suspects. The new Outlook’s built-in Empty option or deleting the RoamCache folder directly clears the blockage without a reinstall.

Search not working. Outlook search depends on a local index built from cached data. If search returns nothing or misses recent mail, clearing the cache and letting it rebuild — followed by reindexing in Windows Search settings — restores results.

Outdated or duplicated items. Seeing old versions of messages, duplicate calendar entries, or unread counts that never change are all signs the local copy has diverged from the server. A fresh cache realigns them.

When clearing the cache does not help — for instance, if the problem also appears on your phone and on the web — the issue is server-side or with the account itself, and you should check service status and account settings instead.

FAQ

Will clearing the Outlook cache delete my emails?

No. When you clear the Outlook cache in Windows 11, your emails are untouched: for Exchange, Microsoft 365, Outlook.com, Gmail, and IMAP accounts, they live on the server and are re-downloaded the next time Outlook syncs. Only POP3 accounts that delete mail from the server are at risk, so back up a POP3 PST file before clearing anything.

How often should I clear the Outlook cache in Windows 11?

There is no need to do it on a schedule — clear the Outlook cache in Windows 11 only when you notice symptoms like sync failures, stuck loading, broken search, or pii_email errors. Most users only need to do it once or twice a year, if ever. Doing it routinely just wastes time re-downloading your mailbox.

Does clearing the cache fix pii_email errors?

Often, yes. Many people clear the Outlook cache in Windows 11 specifically to fix pii_email errors, because they stem from corrupted local data or stale credentials after an update, and clearing the cache plus removing old Office credentials in Credential Manager resolves a large share of them. If the error persists, the cause may be a conflicting add-in or a damaged Office installation that needs a repair.

What is the difference between clearing the cache and reinstalling Outlook?

When you clear the Outlook cache in Windows 11, you remove only temporary local copies of mailbox data and settings. It takes minutes and leaves your accounts and installation intact. Reinstalling Outlook resets the application itself and takes far longer. Try the cache clear first — it fixes the same class of problems with less effort and no risk to your data.

Why does Outlook keep asking for my password after I clear the cache?

That usually means the credential stored in Windows Credential Manager is stale — for example, after a password change — so clearing the Outlook cache in Windows 11 alone will not fix it. Open Credential Manager, remove the MicrosoftOffice and Outlook entries, restart Outlook, and sign in fresh with your current password.

Conclusion

Learning how to clear the Outlook cache in Windows 11 is worth the five minutes it takes, because it resolves a surprising number of common problems: sync failures, stuck loading, broken search, and the pii_email errors that plague users after updates. Start with the method that matches your setup — the built-in Storage option in the new Outlook, the RoamCache folder deletion in classic Outlook, or site-data clearing for Outlook on the web — and add the autocomplete cleanup and Credential Manager reset when the symptoms point that way.

Remember the two rules that keep this safe: close Outlook fully before deleting cache folders, and never delete an OST or PST file for a POP3 account without a backup. With those precautions, clearing the Outlook cache in Windows 11 is the lowest-risk troubleshooting step in your toolkit — and in most cases, the one that gets your inbox working again within minutes.