DrKLO/Telegram · error · IllegalArgumentException

Drawable cannot be null.

Error message

Drawable cannot be null.

What it means

DividerItemDecoration requires a non-null Drawable to draw the divider line; a null mDivider would cause an NPE deep in Canvas.draw during onDraw. setDrawable is annotated @NonNull and checks the argument defensively so the failure is reported at configuration time with a clear message rather than as an opaque NPE during draw. The most common cause is passing getResources().getDrawable(id) which returns null on certain configurations or before resources are ready, or passing a drawable that failed to load.

Source

Thrown at TMessagesProj/src/main/java/androidx/recyclerview/widget/DividerItemDecoration.java:98

     *
     * @param orientation {@link #HORIZONTAL} or {@link #VERTICAL}
     */
    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL && orientation != VERTICAL) {
            throw new IllegalArgumentException(
                    "Invalid orientation. It should be either HORIZONTAL or VERTICAL");
        }
        mOrientation = orientation;
    }

    /**
     * Sets the {@link Drawable} for this divider.
     *
     * @param drawable Drawable that should be used as a divider.
     */
    public void setDrawable(@NonNull Drawable drawable) {
        if (drawable == null) {
            throw new IllegalArgumentException("Drawable cannot be null.");
        }
        mDivider = drawable;
    }

    /**
     * @return the {@link Drawable} for this divider.
     */
    @Nullable
    public Drawable getDrawable() {
        return mDivider;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() == null || mDivider == null) {
            return;
        }
        if (mOrientation == VERTICAL) {

View on GitHub (pinned to 45ab8f4308)

Solutions

1. Resolve the Drawable before passing it and null-check the result.
2. If you need no divider, remove the DividerItemDecoration from the RecyclerView instead of setting a null drawable.
3. Use AppCompatResources.getDrawable(context, R.drawable.x) which never returns null for valid resources (throws otherwise, surfacing the real problem).

Example fix

// before
did.setDrawable(getDrawable(R.drawable.missing)); // may be null

// after
Drawable d = AppCompatResources.getDrawable(this, R.drawable.divider);
if (d != null) {
    did.setDrawable(d);
} else {
    recyclerView.removeItemDecoration(did);
}

// Resolve drawable and guard against null
Drawable d = AppCompatResources.getDrawable(context, resId);
if (d != null) {
    dividerItemDecoration.setDrawable(d);
} else {
    recyclerView.removeItemDecoration(dividerItemDecoration);
}

// Java: null-check at the boundary
boolean isValidDrawable(Drawable d) { return d != null; }

When it happens

Trigger: Passing ContextCompat.getDrawable(context, resId) when resId is 0/invalid; passing a Drawable loaded from a stream that returned null; calling setDrawable(null) intentionally to 'clear' the divider (the API does not support null).

Common situations: Reading a divider resource id from a theme/attr that resolves to 0; using getDrawable on a resource missing from some density buckets; a runtime resource overlay that removed the drawable.

Related errors

• Invalid orientation. It should be either HORIZONTAL or VERTI
• should not dispatch add or move for pre layout
• op should be remove or update.{}
• only remove and update ops can be dispatched in first pass
• Unknown update op type for {}

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/77bbd8de13ff067e. Report an issue: GitHub.