Error map
function main is undeclared in the main package Go: runtime.main_main·f: function main is undeclared in the main package
Go · layer 4, Application & API
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)
failed to solve: process "/bin/sh -c ..." did not complete successfully: exit code: 1
A RUN step in your Dockerfile failed. The real error is printed in the lines just above this message.
dial tcp: lookup registry-1.docker.io: no such host / Temporary failure in name resolution during docker build
DNS isn’t working for the Docker daemon or inside build containers, so pulls and package downloads fail.
failed to solve: failed to read dockerfile: open Dockerfile: no such file or directory
docker build can’t find a Dockerfile in the build context you passed.
Dockerfile parse error line N: unknown instruction
A line in the Dockerfile doesn’t start with a valid instruction — usually a broken line continuation or a typo.
COPY failed: file not found in build context / "/app/x": not found
The Dockerfile COPY refers to a path outside the build context, excluded by .dockerignore, or relative to the wrong directory.
Error response from daemon: max depth exceeded (too many image layers)
The image has more layers than the storage driver allows (127 for overlay2), usually from repeatedly committing containers or ver…
COPY failed: forbidden path outside the build context: ../file
A COPY/ADD tries to read a file above the build context (../something); Docker only sends the context folder to the builder.
Docker build slow: "Sending build context to Docker daemon 2.5GB" / transferring context takes forever
docker build is uploading your whole project folder — node_modules, .git, data files — before building, because there’s no (or a…
Go: ./main.go:5:2: "os" imported and not used
The file imports a package that no code in that file uses; Go treats this as a compile error, not a warning.
Go: ./main.go:12:2: undefined: handler
The compiler cannot find an identifier — a typo, a missing import, or it lives in another file/package that wasn't built.
Go: ./main.go:18:1: missing return
A function with a return type can reach its end without a return statement on some path.
Go: ./main.go:9:6: no new variables on left side of :=
`:=` declares variables, but all names on the left already exist in the same scope.
Two steps away (31)
E: Unable to locate package (apt / apt-get install)
apt can’t find the package name in its package lists — the lists are stale, the repository isn’t enabled, or the name is wrong fo…
Cloudflare Pages build: Error: Output directory "dist" not found / Failed: build output directory not found
The Pages build finished, but the folder set as “Build output directory” doesn’t exist — the framework wrote its files somewhere…
error NETSDK1045: The current .NET SDK does not support targeting .NET 8.0. Either target .NET 7.0 or lower, or use a version of the .NET SDK that supports .NET 8.0
The installed .NET SDK is older than the project’s TargetFramework.
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 408 Request Timeout
The server closed the connection because the client took too long to send the complete request.
TypeError: Failed to fetch / NetworkError when attempting to fetch resource
The browser couldn’t complete the request at the network level — CORS, DNS, offline, blocked mixed content, or the server refused…
error MSB3027: Could not copy "obj\...\App.dll" to "bin\...\App.dll". Exceeded retry count of 10. The file is locked by: "App (1234)"
The build can’t overwrite the output DLL/EXE because the app (or IIS Express, a test runner, antivirus) is still running and hold…
C/C++: undefined reference to `function' — collect2: error: ld returned 1 exit status
The linker can’t find the definition of a function or variable that was declared and used.
Go: cgo: C compiler "gcc" not found: exec: "gcc": executable file not found in $PATH
A package using cgo needs a C compiler, but none is installed or CGO is disabled.
PHP Parse error: syntax error, unexpected …
PHP can’t parse the file because of a syntax mistake — the real error is often on the line before the one reported.
IndentationError: unexpected indent / expected an indented block
Python’s block structure is broken — inconsistent indentation or mixed tabs and spaces.
npm ERR! code ELIFECYCLE / Command failed with exit code 1
An npm script (build, start, test, postinstall) exited with an error. ELIFECYCLE is only the wrapper — the real error is printed…
fatal: not a git repository (or any of the parent directories): .git
You ran a Git command outside a Git working tree.
Error: ENOENT: no such file or directory
A file or directory the program tried to open doesn’t exist at that path.
exec /usr/local/bin/docker-entrypoint.sh: exec format error
The container tried to run a binary built for a different CPU architecture (arm64 vs amd64) — or a script with a broken shebang /…
no space left on device (Docker / Linux)
The disk (or inode table) is full — Docker images, build cache, logs and volumes are common culprits.
no matching manifest for linux/arm64/v8 in the manifest list entries
The image has no build for your CPU architecture — typically pulling an amd64-only image on an Apple Silicon Mac or ARM server.
conflict: unable to remove repository reference (must force) - container is using its referenced image
You tried to delete an image that a container — even a stopped one — still uses.
Go: package app/cmd: no Go files in /app/cmd / build constraints exclude all Go files
The directory you asked Go to build contains no buildable `.go` files.
Cloud Functions: Build failed: function.js does not exist / npm install failed with exit code 1 (Cloud Build step)
The deployment's build step (Cloud Build) failed, so no new function version was created.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
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.
Go: declared and not used: x / "fmt" imported and not used
Go refuses to compile code with unused local variables or unused imports.
Go: cannot assign to struct field users["bob"].Age in map
Map values are not addressable, so you cannot modify a field of a struct stored directly in a map.
Go: invalid operation: a + b (mismatched types int and float64)
You combined two values of different types; Go never converts numeric types implicitly.
Go: cannot use "5" (untyped string constant) as int value in argument to f
A value's type is not assignable to the type required by the variable, parameter or return value.
Go: cannot use &Dog{} (value of type *Dog) as Animal value: *Dog does not implement Animal (missing method Speak)
A type was used as an interface but lacks a method or has it with a different signature or receiver type.
Go: not enough arguments in call to f have (int) want (int, string)
A function was called with fewer or more arguments than it declares.
Go: assignment mismatch: 1 variable but os.Open returns 2 values
The number of variables on the left does not match the number of values the function returns.
Go: ./main.go:8:2: syntax error: unexpected newline, expected comma or )
The parser met a line break where it needed more tokens, usually a missing trailing comma in a multi-line literal or a misplaced…
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