Claude Troubleshooting Practical Manual: Fixes for Blank Pages, Send Failures, and Model Unavailability

If Claude won’t open, keeps spinning, or messages won’t send, it’s usually not that the “account is broken,” but that something is wrong with browser cache, the network route, or session state. Below is a Claude troubleshooting guide organized by the most common symptoms. Follow the steps one by one, and you can usually get back to normal within ten minutes.

Blank page, endless loading: check the browser and network first

When troubleshooting Claude, I first open the same URL in an “incognito window.” If it works there, it’s most likely a cache issue or an extension conflict. Next, clear site data (Cookies/cache), and temporarily disable ad blockers, script managers, and privacy/anti-tracking extensions—these are the most likely to cause Claude to white-screen or for components to load incompletely.

If it still doesn’t work in incognito, try switching networks: move from Wi‑Fi to a mobile hotspot, or vice versa. Common network-side issues include slow DNS resolution or blocking by corporate/campus network policies, which shows up as Claude spinning indefinitely without an error. In that case, using a more reliable DNS or switching to a more open network is often more effective than repeatedly refreshing.

Message failed to send / button greyed out: deal with a stuck session and input anomalies

In Claude troubleshooting, the worst part of “send failed” is losing what you worked hard to write: first copy everything in the input box into Notepad (or another editor), then refresh the page and re-enter the session. If it still fails after refreshing, create a new chat and send again to determine whether it’s “a single conversation stuck” or “a site-wide sending issue.”

Also don’t overlook the input itself: overly long pasted content, unexpected control characters mixed in, or dumping a large number of code blocks at once can all trigger front-end validation, causing the button to turn grey or the send action to be unresponsive. Sending in segments and removing invisible characters (paste into a plain-text editor first, then copy back) are very practical Claude troubleshooting methods.

Model unavailable / very slow responses: check peak congestion and permission status

When Claude indicates a model is unavailable, becomes noticeably slower, or retries frequently, first switch back to a more general model option (if the interface allows switching) or simply start a new chat and resend. During peak-time congestion, repeatedly clicking “Retry” in the same conversation is more likely to compound failures; waiting tens of seconds before trying again usually yields a higher success rate.

If you find that only a specific model can’t be selected while other features are normal, it’s more likely a permissions/quota status change than a local issue. For this kind of Claude troubleshooting, prioritize checking whether the available features on your account page have changed, and avoid asking questions concurrently across multiple devices or multiple tabs to reduce the chance of triggering risk controls or session anomalies.

Attachment/image upload failed: troubleshoot step by step from format and permissions to browser capabilities

When Claude troubleshooting reaches the upload step, first confirm the file itself: convert images to common formats (such as JPG/PNG), and keep documents as standard PDFs or plain text; if the file is too large, compress or split it first. If the button is clickable but nothing happens after selecting a file, a common cause is that the browser’s site permissions have been disabled—especially permissions related to “file access/clipboard/pop-ups.”

You can also try another browser for comparison: if the same account can upload in a different browser, the issue is with the current browser configuration or extensions; if neither works, go back to the network and account status and continue troubleshooting Claude. One final tip: when an upload fails, don’t stare only at the error message—opening the Network panel in the browser’s developer tools can help you quickly pinpoint whether the request was blocked, timed out, or never sent at all.