--- title: "Help center: find the screen you are looking at | Scalebrowser" description: "Answers for what is on your screen: the Windows SmartScreen prompt, signing in a PC, a profile open on another machine, plan limits, tokens and tools for your agent, and every error code, with the page in the docs that goes deeper." canonical: "https://scalebrowser.net/help" last_modified: "2026-11-15T13:22:44.000Z" --- > ## Documentation Index > Fetch the complete documentation index at: https://scalebrowser.net/llms.txt > Use this file to discover all available pages before exploring further. Help center14 answers, every error code # What is on your screen? Find the message you are looking at, and its answer opens next to it. Or search the help and the docs at once. An error code, a word, a message Try ## Answers by screen Install Install Sign in Start a browser Start a browser Start a browser Start a browser Start a browser Plan limits Plan limits Connect an agent Connect an agent Connect an agent Workflows Install ### Windows protected your PC Windows protected your PC Microsoft Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk. More info Don't run 9:41 Expected: choose More info, then Run anyway. The installer has no Windows certificate yet, so Windows asks before it runs it. The release itself is signed, and the app checks every update's signature before it installs it. * [Download, step by step](https://scalebrowser.net/download) * [Install & run](https://scalebrowser.net/docs/install) ## Every error code An error comes back as `{ "code": 4012, "message": "…" }`. 4007 is retired and 4009 does not exist. | Code | What it means | | ---------------------------- | ---------------------------------------------------------------------------------------------------------------------------- | | 4001NOT_FOUND · 404 | [In the Errors page of the docs](https://scalebrowser.net/docs/errors) | | 4002PROXY/GEO · 409 | [In the Errors page of the docs](https://scalebrowser.net/docs/errors) | | 4003CAPACITY · 429 | This machine is full: its maximum, memory budget or free disk space. [See the answer](https://scalebrowser.net/help#pc-full) | | 4004ENGINE_MISSING · 503 | [In the Errors page of the docs](https://scalebrowser.net/docs/errors) | | 4005PREFLIGHT · 409 | A start check failed, such as no real graphics card. [See the answer](https://scalebrowser.net/help#no-gpu) | | 4006ALREADY_RUNNING · 409 | [In the Errors page of the docs](https://scalebrowser.net/docs/errors) | | 4008CONCURRENCY_LIMIT · 409 | Your plan's browsers at once are all running. [See the answer](https://scalebrowser.net/help#browsers-at-once) | | 4010UNAUTHORIZED · 401 | The bearer token is missing or wrong. [See the answer](https://scalebrowser.net/help#token) | | 4011NOT_SIGNED_IN · 403 | No account is connected to this machine. [See the answer](https://scalebrowser.net/help#not-signed-in) | | 4012PROFILE_IN_USE · 409 | The profile runs on another machine of your account. [See the answer](https://scalebrowser.net/help#profile-in-use) | | 4013EXIT_ADDRESS_TAKEN · 409 | The exit address belongs to another profile. [See the answer](https://scalebrowser.net/help#exit-taken) | | 4014PLAN_LIMIT · 409 | Your plan does not allow it. [See the answer](https://scalebrowser.net/help#plan-limit) | ## The docs go deeper * [Test your setup](https://scalebrowser.net/docs/verify) * [Troubleshooting](https://scalebrowser.net/docs/ops/troubleshooting) * [Errors](https://scalebrowser.net/docs/errors) * [Which clients work](https://scalebrowser.net/docs/agents/mcp-clients) What does a website see of your browser? [Run the free browser check](https://scalebrowser.net/check). Ask your agent instead: every docs page has a Markdown twin, and one file lists them all. ## Still stuck? Write to us. Put the error code and the step you were on in your mail. That is where the answer starts. [Write to support](mailto:support@scalebrowser.net?subject=Help%20with%20Scalebrowser\&body=Code%3A%204012%0AApp%20version%3A%200.26.0%0AWhat%20I%20did%3A%20) Enterprise, more than Studio, or white label for your agency? Tosupport\@scalebrowser.net SubjectError 4012 on my second PC *Code: 4012* App version: 0.26.0 What I did: started the profile Shop EU 01 on my office PC.