Import failed. The NinjaScript Archive File may contain duplicate method names that already exist on your PC...

Initial Steps

When the import fails using the standard methods of installing or updating the NinjaScript add-on, then we can try new alternatives, among them manually importing the NinjaScript add-on.

To install manually as alternative, follow the steps below:

• Close Ninjatrader.
• Open the downloaded zip file from our website ProductName-1.X.X.X-xxxxx.zip and copy the ProductName.dll (all .dlls files) file(s) to the location in your computer \Documents\Ninjatrader 8\bin\Custom, click Yes to replace the old file.
• Open Ninjatrader and click Yes to all warning messages.
• Check if you have the latest Product version.

The product is ready to use. Please also make sure that you are not using Microsoft OneDrive with NinjaTrader, as they are incompatible. NinjaTrader and OneDrive Compatibility: A Comprehensive Guide.

Note: OneDrive interference shows up specifically during installs and updates, not during day-to-day use, so a setup that has run fine for months can still fail on the next update. When an add-on is imported, NinjaTrader writes new files into the \Documents\NinjaTrader 8 folder; if OneDrive is syncing that folder, it can lock or virtualize those files at the moment NinjaTrader needs them, which can cause the platform to close mid-import with no error message. As an immediate workaround, pause OneDrive syncing before performing the manual install above.

Extra Steps

Almos sure you are using Microsoft's OneDrive, which is incompatible with NinjaTrader. If this is the case, we would like to invite you to check out our related post via this link and contact NinjaTrader support to resolve the incompatibility issue between OneDrive and NinjaTrader.

For the best assistance, I kindly recommend contacting their support team at support@ninjatrader.com. They are well-equipped to help you resolve this issue.

If the import is blocked by programming errors in other custom scripts

A different error can also stop the import: "You have custom NinjaScript files on your PC that have programming errors. These errors must be resolved before you can import a NinjaScript Archive File." This is not a problem with our product. NinjaTrader compiles your entire NinjaScript library every time it imports an add-on, so if any other custom script on the machine has a compilation error, the import is blocked until that error is cleared.

To find and clear the failing script:

• Open New > NinjaScript Editor and press F5 to compile.
• Check the Errors tab at the bottom of the editor. Each line names the file where the error is located, and double-clicking a line opens that file.
• Right-click only the file(s) the Errors tab names and choose Exclude From Compilation (or Remove if the script is no longer needed). Files whose names start with @ are NinjaTrader system files and should be left alone.
• Press F5 again and repeat until the Errors tab shows no errors.

Once the library compiles with zero errors, import the add-on again and it will go through. NinjaTrader's own guide covers the same steps: How do I resolve NinjaScript Programming Errors?