Claude Troubleshooting Manual: Stuck Spinning, Message Send Failures, and Attachment Issues

When using Claude for writing or organizing research materials, the most annoying things are endless spinning, messages that won’t send, and attachments that just won’t upload. Below, following the order of “first determine whether it’s a service issue — then handle the local environment — finally check account limits,” I’ll explain Claude troubleshooting clearly. Follow these steps and you can usually pinpoint the exact cause.

First, confirm whether Claude is experiencing an outage or congestion

If Claude suddenly slows down across the board and all conversations get stuck, don’t rush to reinstall your browser. Check the service status page first (you can look it up on Anthropic’s status page). When the status page shows Degraded/Incident, no matter what you do locally it’s hard to recover immediately—you can only wait for an official fix or try again later.

At the same time, switch networks for cross-checking: if the same account behaves completely differently on a mobile hotspot versus company Wi‑Fi, it’s usually due to the network path or policy blocking that causes Claude requests to time out. If Claude works normally on another network, the direction for troubleshooting becomes very clear.

Common fixes for Claude endlessly spinning and message send failures

If Claude keeps spinning after you click send, it’s commonly due to browser cache, extension scripts, or abnormal cookie state. First, open an incognito window and log in to Claude to try once; if it works in incognito, the issue is most likely caused by extensions or cache.

Next, disable ad blockers, script managers, and privacy/anti-tracking extensions one by one, then refresh the Claude page and try again. If it still doesn’t work, clear the site’s cache and cookies and log back in to Claude; this step resolves many issues where it “looks online but can’t send messages.”

How to troubleshoot Claude attachment upload failures and parsing errors

Claude attachment failures are generally related to format, file size, encoding, or upload interruptions on the network. Start by following the on-page prompts to convert the file to a more common format (e.g., convert scanned documents to clear PNGs, or organize multi-page documents into a standard PDF), and try uploading again after compressing.

If it’s “uploaded successfully but cannot be parsed,” it’s more reliable to split the file into smaller sections or volumes and re-upload. Another practical approach is to copy the key information into plain text and send it to Claude first to confirm the chat function works, then come back to deal with the attachment itself.

When you see 403/429/5xx: handling by type is faster

A 403 with Claude is mostly related to access region, network egress, or risk-control policies: first switch networks, log out and back into Claude, and make sure your browser isn’t using tools that interfere with location/access policies. If multiple accounts on the same network all get 403, it’s usually not that the account is broken—it’s that the network environment isn’t accepted.

429 indicates too many requests or hitting a limit in a short time; the most effective approach is to reduce concurrency, refresh less frequently, avoid repeated sends, and wait a while before using Claude again. 5xx tends to be server-side fluctuation: save what you typed, retry later or use Claude at a different time—this often saves more time than repeatedly refreshing.