DrKLO/Telegram · error · IllegalStateException

Cannot call this method while RecyclerView is computing a la

Error message

Cannot call this method while RecyclerView is computing a layout or scrolling

What it means

assertNotInLayoutOrScroll(null) is the inverse guard: it forbids methods that must NOT run during a layout or scroll pass (e.g. setAdapter, setLayoutManager, setHasFixedSize, adapter data-set calls that re-trigger layout). If isComputingLayout() is true and no message was supplied, it throws 'Cannot call this method while RecyclerView is computing a layout or scrolling'. Re-entrant layout mutations corrupt the in-flight pass.

Source

Thrown at TMessagesProj/src/main/java/androidx/recyclerview/widget/RecyclerView.java:3057

                throw new IllegalStateException("Cannot call this method unless RecyclerView is "
                        + "computing a layout or scrolling" + exceptionLabel());
            }
            throw new IllegalStateException(message + exceptionLabel());

        }
    }

    /**
     * Checks if RecyclerView is in the middle of a layout or scroll and throws an
     * {@link IllegalStateException} if it <b>is</b>.
     *
     * @param message The message for the exception. Can be null.
     * @see #assertInLayoutOrScroll(String)
     */
    void assertNotInLayoutOrScroll(String message) {
        if (isComputingLayout()) {
            if (message == null) {
                throw new IllegalStateException("Cannot call this method while RecyclerView is "
                        + "computing a layout or scrolling" + exceptionLabel());
            }
            throw new IllegalStateException(message);
        }
        if (mDispatchScrollCounter > 0) {
            Log.w(TAG, "Cannot call this method in a scroll callback. Scroll callbacks might"
                            + "be run during a measure & layout pass where you cannot change the"
                            + "RecyclerView data. Any method call that might change the structure"
                            + "of the RecyclerView or the adapter contents should be postponed to"
                            + "the next frame.",
                    new IllegalStateException("" + exceptionLabel()));
        }
    }

    /**
     * Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched
     * to child views or this view's standard scrolling behavior.
     *

View on GitHub (pinned to 45ab8f4308)

Solutions

1. Defer structural changes out of the layout/scroll pass: use recyclerView.post(() -> adapter.notifyDataSetChanged()).
2. For pagination, set a pending flag in onScrolled and apply new data on the next frame.
3. Never call setAdapter/setLayoutManager from within onLayoutChildren or ItemDecoration callbacks.

Example fix

// before
recyclerView.addOnScrollListener(new OnScrollListener() {
    @Override public void onScrolled(RecyclerView rv, int dx, int dy) {
        if (atBottom) adapter.loadMore(); // may call notify* during layout
    }
});

// after
recyclerView.addOnScrollListener(new OnScrollListener() {
    @Override public void onScrolled(RecyclerView rv, int dx, int dy) {
        if (atBottom && !pendingLoad) {
            pendingLoad = true;
            rv.post(() -> { adapter.loadMore(); pendingLoad = false; });
        }
    }
});

Runnable structuralChange = () -> {
    adapter.notifyDataSetChanged(); // or setAdapter / setLayoutManager
};
if (recyclerView.isComputingLayout()) {
    recyclerView.post(structuralChange);
} else {
    structuralChange.run();
}

null

null

When it happens

Trigger: Calling setAdapter, swapAdapter, setLayoutManager, or adapter.notify* from inside onLayoutChildren of a custom LayoutManager, from an ItemDecoration.onDraw, or from a scroll listener that triggers a data mutation.

Common situations: Adapter swap triggered inside a scroll listener (onScrolled) that itself runs during layout. Custom LayoutManager that calls recyclerView.setAdapter during layout. Infinite scroll that calls notifyDataSetChanged synchronously inside onScrolled.

Related errors

• Cannot call this method unless RecyclerView is computing a l
• {message}
• Called attach on a child which is not detached: {vh}
• called detach on an already detached child {vh}
• LayoutManager {layout} is already attached to a RecyclerView

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/bb654b8faa34397c. Report an issue: GitHub.