> For the complete documentation index, see [llms.txt](https://docs.clipper.exchange/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.clipper.exchange/disclaimers-and-technical/integrating-with-clipper-rfq/troubleshooting-and-faqs.md).

# Troubleshooting & FAQs

### **403 Error with message “Unknown sender\_address” in sign API**

* The **sender\_address** is detected as unsafe (possibly bot).
* If the client is using a contract as router for the quote we need to whitelist the contract address in order to bypass the bot check.