This error is commonly encountered in C++ when you’re trying to initialize a non-const reference with an rvalue. This isn’t allowed because non-const references are meant to be able to modify their underlying objects, but rvalues are temporary objects and typically can’t be modified safely.

To illustrate:

“`C++
int& ref = 5; // error: initial value of reference to non-const must be an lvalue
“`

Here, ‘5’ is a temporary value, an rvalue, and C++ prevents you from doing this because if the language allowed binding a non-const lvalue reference to an rvalue, the temporary could be changed via the reference, which is unsafe and goes against the identifier’s temporary nature.

The way to solve this issue or avoid this error message depends on what you’re trying to do:

– If you really need your reference to point to the value and you promise not to change it, you could use a const reference instead:

“`C++
const int& ref = 5; // OK
“`

– If you need to modify the value through the reference, you should assign the value to a named variable (an lvalue) first:

“`C++
int val = 5;
int& ref = val; // OK
“`

– If it is a function does not modify its argument, but takes it by reference, you can make your parameter a const reference:

“`C++
void func(const int& num) {
// function implementation
}
“`

Keep in mind that this change will invoke a different semantic meaning and potential implications on the lifespan of the rvalue, so it’s crucial to understand the reason behind your error before applying the solution.