Why My Gemini API Key Failed in Cursor and How I Got Gemini 2.5 Pro Experimental Working

As an AI developer, I’m always hunting for the latest tools. So when Google released Gemini 2.5 Pro Experimental, I was excited! I wanted to add it to my Cursor IDE right away for better coding and reasoning.

But then I hit a frustrating API key error. It almost stopped me in my tracks. Here’s how I fixed the problem and got everything working.

The Problem That Stopped Me

I set up my Gemini API key in Cursor, but then I kept seeing this cryptic error. It completely blocked me from using the model. Here’s what the error said:

{
"error": {
"code": 404,
"message": "models/gemini-1.0-pro is not found for API version v1beta, or is not supported for generateContent. Call ListModels to see the list of available models and their supported methods.",
"status": "NOT_FOUND"
}
}

This meant Cursor couldn’t find the model. And I couldn’t use Gemini 2.5’s awesome features, like its huge 65,536-token output.

My Step-by-Step Solution

After some experimenting, I found a solid fix using OpenRouter. Here’s exactly how I got Gemini 2.5 Pro Experimental working in Cursor:

1. Sign up for OpenRouter: I went to openrouter.ai and created a free account. OpenRouter is a gateway to many AI models, including Gemini.
2. Add the Gemini model in OpenRouter: In my OpenRouter dashboard, I clicked “Add Model” and entered the exact identifier: gemini-2.5-pro-exp-03-25. That way I got the latest experimental version.
3. Configure in Cursor: Back in Cursor, I opened settings. Instead of the Gemini key, I added my OpenRouter API key. Then, from the models dropdown, I picked Gemini.
4. Test it out: I tried a simple coding prompt. It worked perfectly! The reasoning and coding improvements were impressive.

Why It’s Worth the Effort

Now that I have Gemini 2.5 Pro Experimental running, it’s a total upgrade. Compared to models like Sonnet, it handles complex tasks way better. Responses are faster and more accurate.

Here’s the best part: you can use this model for free with your own key. But using OpenRouter avoids compatibility headaches. If you work with AI, the setup time is worth the boost in productivity.

Try it out! I think you’ll be amazed at how it changes your Cursor experience.