ppy/osu · error · InvalidOperationException

Attempting to save a skin which is not yet tracked. Call {na

Error message

Attempting to save a skin which is not yet tracked. Call {nameof(EnsureMutableSkin)} first.

What it means

Thrown by SkinManager.Save(skin) when skin.SkinInfo.IsManaged is false, meaning the Skin has not been attached to the realm store. Saving requires the SkinInfo to be a tracked realm entity so changes can be persisted; an untracked skin cannot be serialized back.

Source

Thrown at osu.Game/Skinning/SkinManager.cs:293

                    // save once to ensure the required json content is populated.
                    // currently this only happens on save.
                    result.PerformRead(skin => Save(skin.CreateInstance(this)));
                    CurrentSkinInfo.Value = result;
                    return true;
                }

                return false;
            });
        }

        /// <summary>
        /// Save a skin, serialising any changes to skin layouts to relevant JSON structures.
        /// </summary>
        /// <returns>Whether any change actually occurred.</returns>
        public bool Save(Skin skin)
        {
            if (!skin.SkinInfo.IsManaged)
                throw new InvalidOperationException($"Attempting to save a skin which is not yet tracked. Call {nameof(EnsureMutableSkin)} first.");

            return skinImporter.Save(skin);
        }

        /// <summary>
        /// Perform a lookup query on available <see cref="SkinInfo"/>s.
        /// </summary>
        /// <param name="query">The query.</param>
        /// <returns>The first result for the provided query, or null if no results were found.</returns>
        public Live<SkinInfo> Query(Expression<Func<SkinInfo, bool>> query)
        {
            return Realm.Run(r => r.All<SkinInfo>().FirstOrDefault(query)?.ToLive(Realm));
        }

        public event Action SourceChanged;

        public Drawable GetDrawableComponent(ISkinComponentLookup lookup) => lookupWithFallback(s => s.GetDrawableComponent(lookup));

View on GitHub (pinned to d9c73e12ad)

Solutions

Call skinManager.EnsureMutableSkin() before Save() to guarantee the skin is tracked and mutable.
If operating on the current skin, ensure the user has selected a non-default (mutable) skin.
Wrap Save in the same flow that promotes a live skin to a tracked SkinInfo.

Example fix

// before
skinManager.Save(skin);

// after
skinManager.EnsureMutableSkin(() =>
{
    skinManager.Save(skin);
});

Defensive patterns

Strategy: validation

Validate before calling

if (!skin.SkinInfo.IsManaged)
    throw new InvalidOperationException("Call EnsureMutableSkin before Save.");

Type guard

static bool IsSkinTracked(Skin s) => s.SkinInfo.IsManaged;

Try / catch

try { skinManager.Save(skin); }
catch (InvalidOperationException) { skinManager.EnsureMutableSkin(() => skinManager.Save(skin)); }

Prevention

Call EnsureMutableSkin before Save.
Avoid saving the default/argon skin directly.
Promote skins to tracked entities before edits.

When it happens

Trigger: Calling Save() on a Skin that was constructed in-memory (e.g. default skin or a newly created one) without first making it tracked via EnsureMutableSkin().

Common situations: Editing the default/argon skin in-place (which is read-only/untracked); creating a Skin programmatically and trying to save before registering it; forgetting to call EnsureMutableSkin in an editor flow.

Related errors

AI-assisted analysis of ppy/osu@d9c73e12ad (2026-08-13). Data as JSON: /api/errors/60c1bd9382189bd0. Report an issue: GitHub.