How to clear the NinjaTrader cache

Clearing the NinjaTrader cache forces NinjaTrader to discard its locally stored historical data and re-download it from the data provider. This is a procedural reference — use it only when you've been directed to do so (by Vector support, or because you're following an article that calls for it). Cache clearing is not a general fix for slow performance and shouldn't be done on a whim.

Before you start

• Make sure no strategies are in the middle of an open trade or expected to fire imminently. Clearing the cache requires NinjaTrader to be fully closed.
• This step removes locally cached historical data only. It does not touch your strategies, templates, workspaces, or settings — those are stored separately.

Procedure

1. Close NinjaTrader completely. Make sure no NinjaTrader process is still running — check the system tray (bottom-right of your VPS taskbar) and end any leftover instance.
2. Open File Explorer and navigate to Documents\NinjaTrader 8\db\cache.
3. Delete the files inside the cache folder. Select all files and delete them. Do not delete the cache folder itself — only its contents.
4. Reopen NinjaTrader. It will rebuild the cache automatically as data flows in from your broker.

What to expect after

• Charts may take longer to load the first time you open them, since NinjaTrader needs to re-pull the historical data from your provider.
• Strategy parameters, chart templates, and workspace layouts are unchanged.
• If anything appears wrong after the cache rebuild — strategies don't re-enable on their own, charts don't fill in, account info missing — open a ticket at http://support.vectoralgorithmics.io/.

What this is not

Cache clearing is a narrow procedure with a specific purpose. It is not the same as:

• Resetting the NinjaTrader database (Control Center → Tools → Database Management). That is a much broader action that affects more than the cache and should only be done in specific situations the team will direct you through (for example, contract rollover handling — see: Why Didn't My Strategy Fire Today?).
• Reinstalling NinjaTrader. That's a different procedure handled by the team if needed.

If you're unsure whether cache clearing is the right step for your situation, open a ticket first — the team will tell you what to do.

Advanced: clearing the Windows DNS cache

Separate from the NinjaTrader cache, there's another cache at the Windows level — the DNS cache — that occasionally causes issues with network lookups. When a persistent connection issue to a broker or data provider doesn't resolve after the usual steps (reconnect, check data feed status), flushing the Windows DNS cache on the VPS can help clear stale network records.

This is a separate action from clearing the NinjaTrader cache above.

To flush the Windows DNS cache:

1. On your VPS, press Windows Key + R to open the Run dialog.
2. Type cmd and press Enter to open the Command Prompt.
3. Type ipconfig /flushdns and press Enter.
4. You should see the message "Successfully flushed the DNS Resolver Cache."

This is non-destructive — it doesn't touch NinjaTrader, your strategies, or any trading settings. It simply forces Windows to drop any stored DNS lookups and fetch them fresh on the next connection attempt.

As with the NinjaTrader cache, this is only a useful step in specific scenarios. If you're not sure whether it applies to your issue, open a ticket first.

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