> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-software/troubleshoot/command-centre-errors/command-centre-errors-site-in-read-onl.md). # Site in Read Only - No Key Devices Online [Command Centre - Errors](/knowledge-hub/products/cc-software/troubleshoot/command-centre-errors.md) › Site in Read Only - No Key Devices Online ## What is a Key Device? In a Command Centre system there will be either one or two Gallagher Controllers tagged by their MAC address in the licence, indicating they are a Key Device. At least one of those devices must be online to the server for it to function correctly. If both Key Devices, or the only Key Device, are offline for **30 days**, the system goes into **Read Only** mode and you cannot modify the site. ## When the site is read-only If the site has gone read-only because the Key Device controllers are offline, the only item still editable is the controller's **Setup** tab. This lets you reconfigure an existing controller with a new MAC address to match a new licence that has a new Key Device added. When the site is in read only, Command Centre continues to run normally, but you cannot make configuration changes. ## Resolution If the Key Devices went offline due to network issues, resolve the network issue to bring the system back into normal operation. Before the site goes read-only, warning alarms are generated within minutes of one or both Key Devices losing network communication. > **Recommendation:** Keep the Key Device controllers as close as possible to the server to reduce the likelihood of a network issue causing the system to end up in Read Only. > **Note:** To get a licence updated with a new Key Device, Gallagher requires the old controller to be returned promptly. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://help.security.gallagher.com/knowledge-hub/products/cc-software/troubleshoot/command-centre-errors/command-centre-errors-site-in-read-onl.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.