Error map
503 HTTP 503 Service Unavailable
HTTP · layer 2, Network
Centre: this error. First ring: errors it is linked with (12). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (12)
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
API Service Unavailable
The API service is temporarily unable to process requests because the service is unavailable, overloaded, or undergoing maintenan…
WordPress: Briefly unavailable for scheduled maintenance. Check back in a minute.
An update was interrupted and WordPress left its `.maintenance` file behind, so the site stays in maintenance mode.
LLM API: overloaded_error (529) / The server is overloaded / Service unavailable — model temporarily overloaded
The provider is temporarily at capacity; the request was rejected even though your key and quota are fine.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
HTTP 508 Loop Detected (Resource Limit Is Reached)
Either the server detected an infinite loop (WebDAV) or — much more often — a cPanel/CloudLinux host is saying your account hit i…
S3 SlowDown: Please reduce your request rate (503)
S3 is throttling requests to a prefix because the request rate is above what it can currently serve.
Elastic Beanstalk: Environment health has transitioned from Ok to Severe
Most instances in the Elastic Beanstalk environment are failing health checks or returning errors.
Azure Front Door: Our services aren't available right now (503/502 from Front Door)
Front Door couldn’t get a valid response from your origin — origin down, health probes failing, TLS/host header mismatch, or a ti…
Cloudflare Error 1200: Cache connection limit
Too many requests are queued at Cloudflare for the origin — the origin is slow and connections pile up.
HTTP 429 Too Many Requests
You’ve hit a rate limit — too many requests in a given time window. Slow down and retry later.
HTTP 502 Bad Gateway
A proxy or gateway (Nginx, load balancer, CDN) got an invalid response — or no response — from the upstream server behind it.
Two steps away (33)
HTTP 404 Not Found
The server can’t find anything at the requested URL.
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
PHP Fatal error: Allowed memory size of X bytes exhausted
The script tried to use more memory than PHP’s `memory_limit` allows.
PHP Fatal error: Maximum execution time of 30 seconds exceeded
The script ran longer than `max_execution_time` and PHP stopped it.
WordPress: There Has Been a Critical Error on This Website
A PHP fatal error (usually from a plugin or theme) stopped WordPress; the real error is in the debug log or recovery-mode email.
warning: There are too many unreachable loose objects; run 'git prune' to remove them.
Git’s automatic garbage collection found many unreachable objects and is asking you to prune.
API Error: Idempotency key reused with different parameters (idempotency_key_in_use)
An Idempotency-Key header was sent again with a different request body, or while the first request with that key was still runnin…
API Error: Too many concurrent requests (concurrency limit reached)
You have more requests in flight at once than the API allows for your key — even if your requests-per-minute rate is fine.
API Error: Job / operation not found or expired (async task ID unknown)
The status URL or job ID for an asynchronous operation (export, import, render, batch) doesn’t exist any more, or never existed.
HTTP 408 Request Timeout
The server closed the connection because the client took too long to send the complete request.
HTTP 499 Client Closed Request (Nginx)
Nginx-specific code logged when the client disconnected before the server finished responding.
Cloudflare Error 522: Connection Timed Out
Cloudflare’s TCP connection to your origin timed out — the origin didn’t answer at all.
MySQL ERROR 1040 (08004): Too many connections
MySQL reached `max_connections` and refuses new clients.
Azure: SkuNotAvailable / QuotaExceeded when creating a VM or resource
The VM size isn’t offered in that region/zone for your subscription, or you’ve hit the vCPU quota.
MySQL ERROR 1114 (HY000): The table 'x' is full
MySQL couldn’t extend the table — disk full, a size limit, or a MEMORY table hitting max_heap_table_size.
AWS S3: AccessDenied (403) when calling GetObject / PutObject
An IAM policy, bucket policy, ACL/ownership setting, Block Public Access or KMS key policy denied the S3 request.
AWS: ThrottlingException / Rate exceeded
You exceeded the request rate for an AWS API; retry with exponential backoff.
AWS S3: NoSuchKey / NoSuchBucket — The specified key/bucket does not exist
S3 found no object at that key (or no bucket with that name in the region/account you’re calling).
Stack is in ROLLBACK_COMPLETE state and can not be updated
The stack’s first creation failed and rolled back; a stack in ROLLBACK_COMPLETE can only be deleted, not updated.
CloudFormation stack in UPDATE_ROLLBACK_FAILED
An update failed, and then the rollback also failed, leaving the stack stuck until you continue the rollback.
SES MessageRejected: Email address is not verified. The following identities failed the check in region
SES refused to send because the From address/domain isn’t verified — or the account is still in the SES sandbox, where recipients…
Cloudflare Error 520: Web Server Returned an Unknown Error
Cloudflare connected to your origin, but the origin returned an empty, unknown or invalid response.
CloudFront: 403 ERROR — The request could not be satisfied
CloudFront refused or couldn’t serve the request — wrong alternate domain/certificate, blocked by origin access settings, a WAF/g…
AADSTS50020: User account from identity provider does not exist in tenant and cannot access the application
The signed-in user belongs to another tenant (or is a personal Microsoft account) and isn’t a guest in the app’s tenant.
Cloudflare Error 524: A Timeout Occurred
Cloudflare connected to the origin, but the origin didn’t send an HTTP response within 100 seconds.
HTTP 304 Not Modified
The cached copy is still valid, so the server sends no body and the client reuses its cache.
HTTP 412 Precondition Failed
A conditional request header (If-Match, If-Unmodified-Since) didn’t match the current state of the resource.
Kubernetes: ImagePullBackOff / ErrImagePull
The node can’t pull the container image — wrong name/tag, missing registry credentials, or registry unreachable.
HTTP 403 Forbidden
The server understood the request but refuses to authorize it — you (or the server process) are not allowed to access this resour…
Cloudflare Error 1020: Access Denied
A Cloudflare firewall/WAF custom rule blocked the request — the visitor’s IP, country, user agent or request pattern matched a bl…
Error: connect ECONNREFUSED 127.0.0.1:5432
Nothing is listening at that host:port — the target service is down or you’re connecting to the wrong address.
HTTP 407 Proxy Authentication Required
A proxy between you and the server requires credentials before it will forward your request.
Cloudflare Error 521: Web Server Is Down
Cloudflare couldn’t connect to your origin — the connection was refused.
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