Error map
is only available in iOS x or newer Swift: 'X' is only available in iOS 16.0 or newer
iOS · layer 1, On your device
Centre: this error. First ring: errors it is linked with (9). 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 (9)
Swift: The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions
A long expression (often in a SwiftUI body) has too many possible type combinations for the compiler — or hides a type error.
Swift: Cannot convert value of type 'X' to expected argument type 'Y'
The value’s type doesn’t match what the function or property expects.
Swift: Type of expression is ambiguous without a type annotation (more context)
The compiler can’t infer which type you mean — often because of a typo or a wrong argument elsewhere in the expression.
Swift: Escaping closure captures mutating 'self' parameter
A mutating method of a struct tries to capture self in an escaping closure, which Swift forbids.
Swift: Reference to property 'x' in closure requires explicit use of 'self' to make capture semantics explicit
In an escaping closure inside a class, Swift requires self. to make the capture (and potential retain cycle) visible.
Swift 6: Main actor-isolated property 'x' can not be referenced from a nonisolated context / Sending 'x' risks causing data races
Strict concurrency checking found code that accesses main-actor state from another isolation domain, or passes non-Sendable value…
Swift: Fatal error: Index out of range
Code accessed an array index that doesn’t exist — empty arrays, off-by-one loops, or data changing while a table reloads.
Swift: Could not cast value of type 'X' to 'Y'
A force cast (as!) failed because the object isn’t the expected type.
Swift: No such module 'X' (module not found)
Xcode can’t find a Swift package, pod or framework you import.
Two steps away (21)
error CS0246: The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)
The compiler doesn’t know the type — missing using, missing NuGet package/project reference, or a target framework mismatch.
error CS0103: The name 'x' does not exist in the current context
The identifier isn’t declared in scope — typo, variable declared in another block, missing using static, or a Razor/partial class…
error CS1061: 'X' does not contain a definition for 'Y' and no accessible extension method 'Y' accepting a first argument of type 'X' could be found
The member you call doesn’t exist on that type — typo, wrong type, missing using for an extension method, or an API removed in a…
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
java.lang.ClassCastException: class A cannot be cast to class B
An object was cast to a type it isn’t.
TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type.
The JavaScript package has no TypeScript types bundled and no @types package installed.
warning CS8618: Non-nullable property 'X' must contain a non-null value when exiting constructor. Consider declaring the property as nullable
With nullable reference types enabled, a non-nullable reference property isn’t initialised by the constructor.
Go: declared and not used: x / "fmt" imported and not used
Go refuses to compile code with unused local variables or unused imports.
Rust: error[E0308]: mismatched types — expected `X`, found `Y`
A value’s type doesn’t match what the context expects — common with &str vs String, Option/Result vs plain values, and integer ty…
SwiftUI: Publishing changes from background threads is not allowed; make sure to publish values from the main thread
An ObservableObject’s @Published property was updated from a background thread.
Main Thread Checker: UI API called on a background thread: -[UIView setNeedsLayout]
UIKit was used from a background thread; UI must only be touched on the main thread.
Go: fatal error: all goroutines are asleep - deadlock!
Every goroutine is blocked waiting (on a channel, mutex or WaitGroup), so the program can never continue.
Fatal error: Unexpectedly found nil while unwrapping an Optional value
Swift force-unwrapped (`!`) an optional that was nil, crashing the app.
ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection
Code accessed a List/collection position that doesn’t exist (IndexOutOfRangeException for arrays).
.NET: Stack overflow. / Process is terminated due to StackOverflowException
Infinite or very deep recursion exhausted the thread’s stack; .NET can’t catch it and terminates the process.
Illegal instruction (core dumped) (SIGILL)
The program used a CPU instruction your processor doesn’t support — typically AVX/AVX2 in prebuilt binaries (TensorFlow, MongoDB…
The application was unable to start correctly (0xc0000142)
A DLL the program loads failed to initialise — often after an update, with corrupt runtimes, or when a desktop heap/session limit…
System.InvalidCastException: Unable to cast object of type 'X' to type 'Y'
An explicit cast failed because the object’s runtime type isn’t the target type.
CocoaPods could not find compatible versions for pod
pod install can’t satisfy the version constraints — outdated spec repo, a higher deployment target required, or two pods needing…
Signing for "App" requires a development team. Select a development team in the Signing & Capabilities editor
No Apple developer team is selected for the target, so Xcode can’t sign the app.
Undefined symbol(s) for architecture arm64 — linker command failed with exit code 1
The linker can’t find the implementation of a symbol your code uses — a missing framework/library, a file not in the target, or a…
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