Umbrella issue for 26.0 testing. Please help testing on a wide variety of supported platforms, as well as interaction with different software.

Let us know which version you tested on which operating system.

If you find an issue, please search Github for known issues first and then open a new Github issue.

*This meta issue should not be used to report bugs, as a single thread makes it impossible to track more than one topic.*

See [26.0 Draft Release Notes](https://github.com/bitcoin-core/bitcoin-devwiki/wiki/26.0-Release-Notes-Draft) for a list of changes.

See here for the testing guide: https://github.com/bitcoin-core/bitcoin-devwiki/wiki/26.0-Release-Candidate-Testing-Guide.
{
        return (bytes + ELEM_ALIGN_BYTES - 1) / ELEM_ALIGN_BYTES + (bytes == 0);
    }
    /**
     * True when it is possible to make use of the freelist
     */
    [[nodiscard]] static constexpr bool IsFreeListUsable(std::size_t bytes, std::size_t alignment)
    {
        return alignment <= ELEM_ALIGN_BYTES && bytes <= MAX_BLOCK_SIZE_BYTES;
    }
    /**
     * Replaces node with placement constructed ListNode that points to the previous node
     */
    void PlacementAddToList(void* p, ListNode*& node)
    {
        node = new (p) ListNode{node};
    }
    /**
     * Allocate one full memory chunk which will be used to carve out allocations.
     * Also puts any leftover bytes into the freelist.
     *
     * Precondition: leftover bytes are either 0 or few enough to fit into a place in the freelist
     */
    void AllocateChunk()