C++: pure virtual method called — terminate called without an active exception

Meaning

During a base-class constructor or destructor the object's dynamic type is the base, so a virtual call resolves to the base version — which is pure and has no body. The same happens when another thread calls a method on an object that is mid-destruction, or after the object has been deleted.

Common causes

• Calling a virtual function from a base-class constructor or destructor
• Object used after delete (dangling pointer)
• Thread calling methods while the object is destroyed
• Slicing a derived object to its base

Detailed fix by platform

Code examples

struct Base {
    Base()  { setup(); }              // calls Base::setup (pure!) during construction
    virtual void setup() = 0;
    virtual ~Base() = default;
};
struct Derived : Base {
    void setup() override {}
};
// Derived d;  -> "pure virtual method called" / terminate

// Fix: call setup() after construction, e.g. Derived d; d.setup();

How to diagnose

1. Context — Called from a constructor or destructor?
2. Lifetime — Could the object already be deleted?
3. Threads — Another thread using it?

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