Error map
Malformed Lambda proxy response API Gateway {"message": "Internal server error"} 502 — Malformed Lambda proxy response
AWS · layer 6, Platform & cloud
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.
AWS Lambda: Task timed out after X seconds
The function ran longer than its configured timeout (default 3 seconds) and Lambda stopped it.
API Gateway: {"message": "Endpoint request timed out"} (504 after 29 seconds)
The backend (usually Lambda) didn’t respond within API Gateway’s integration timeout (29 seconds by default for REST APIs).
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…
Lambda: Request must be smaller than 6291456 bytes for the InvokeFunction operation (RequestEntityTooLargeException)
The event payload (or response) is over Lambda’s 6 MB synchronous limit (256 KB for async invocations).
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.
API Gateway 403: User is not authorized to access this resource with an explicit deny
An API Gateway authorizer (Lambda/Cognito) or resource policy denied the request.
InvalidParameterValueException: The role defined for the function cannot be assumed by Lambda
The execution role’s trust policy doesn’t allow lambda.amazonaws.com — or the role was just created and IAM hasn’t propagated yet.
Runtime.ImportModuleError: Unable to import module 'lambda_function': No module named 'x'
Lambda couldn’t load your handler file or one of its dependencies — the package is missing from the deployment zip/layer or the h…
Runtime.HandlerNotFound: index.handler is undefined or not exported
Lambda loaded the file but couldn’t find the function named in the handler setting.
Lambda: Runtime exited with error: signal: killed (Runtime.ExitError)
The function process was killed — almost always because it ran out of its configured memory.
Lambda: Unzipped size must be smaller than 262144000 bytes
The function code plus layers exceed Lambda’s 250 MB unzipped limit for zip deployments.
Two steps away (36)
HTTP 404 Not Found
The server can’t find anything at the requested URL.
HTTP 503 Service Unavailable
The server is temporarily unable to handle the request — overloaded, in maintenance, or has no healthy backends.
SyntaxError: Unexpected token < in JSON at position 0
`JSON.parse()` / `response.json()` received something that isn’t JSON — very often an HTML error page.
AWS: ThrottlingException / Rate exceeded
You exceeded the request rate for an AWS API; retry with exponential backoff.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
java.util.concurrent.TimeoutException
A Future.get(timeout) or async operation didn’t complete in the allowed time.
MySQL ERROR 2006 (HY000): MySQL server has gone away
The connection to MySQL was closed — usually by a timeout or a packet larger than `max_allowed_packet`.
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.
PHP mail() returns false / emails not delivered
PHP’s mail() function failed or emails never arrive (spam or rejected).
AccessDeniedException: User: arn:aws:iam::... is not authorized to perform: service:Action on resource: ...
The IAM user or role making the call has no permission for that action on that resource — the message names both.
ACM certificate stuck in Pending validation
ACM is waiting to see the DNS (or email) validation record — it wasn’t created, was created in the wrong DNS zone, or has a typo.
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
Too many open files (EMFILE)
The process hit its file-descriptor limit — sockets, files and pipes all count.
fork: retry: Resource temporarily unavailable (process/thread limit)
The user or container hit its maximum number of processes/threads (ulimit -u, pids cgroup), so new processes can’t be created.
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 520: Web Server Returned an Unknown Error
Cloudflare connected to your origin, but the origin returned an empty, unknown or invalid response.
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.
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…
Azure: AuthorizationFailed — The client does not have authorization to perform action
The signed-in identity (user, service principal or managed identity) lacks an Azure RBAC role for that action on that scope.
WordPress: Sorry, you are not allowed to access this page.
Your user role lacks the capability for that admin screen — or the database table prefix / user capabilities are out of sync afte…
is not authorized to perform: sts:AssumeRole on resource: arn:aws:iam::...:role/...
The caller can’t assume the role — either its own policy doesn’t allow sts:AssumeRole, or the role’s trust policy doesn’t trust t…
KMS: not authorized to perform: kms:Decrypt (or the key policy does not allow access)
The caller can’t use the KMS key that encrypts the data — the key policy or IAM policy doesn’t allow kms:Decrypt/GenerateDataKey.
npm ERR! code ERESOLVE — unable to resolve dependency tree
npm 7+ found conflicting peer dependency requirements and refuses to install a broken tree.
Error: Cannot find module 'x' (MODULE_NOT_FOUND)
Node can’t resolve the module path — the package isn’t installed, or a relative path/extension is wrong.
Gradle: Could not resolve all files for configuration / Could not resolve dependency
Gradle couldn’t download a dependency — wrong coordinates/version, missing repository, offline mode, or network/proxy issues.
TypeError: x is not a function
You called something as a function, but its value is not a function (it’s undefined, a string, an object…).
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
WordPress: Error Establishing a Database Connection
WordPress can’t connect to its MySQL/MariaDB database with the credentials in wp-config.php, or the database server is down.
Kubernetes: OOMKilled (exit code 137)
The container used more memory than its limit, and the kernel killed it.
java.lang.OutOfMemoryError: Java heap space
The JVM ran out of heap memory and garbage collection couldn’t free enough.
Blue Screen: MEMORY_MANAGEMENT (Stop code 0x0000001A)
Windows detected a severe memory-management error — commonly faulty RAM, unstable memory settings or a bad driver.
Cloudflare Error 1025: Please check back later (Workers request limit)
The site’s Cloudflare Workers plan exceeded its daily request limit (free plan: 100,000 requests/day).
Cloudflare Error 1102: Worker exceeded resource limits (CPU time / memory)
The Worker used more CPU time or memory than its plan allows for a single request.
Cloudflare 413 Request Entity Too Large (upload over the plan limit)
The request body is larger than Cloudflare allows through the proxy — 100 MB on Free/Pro, 200 MB Business, 500 MB Enterprise defa…
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