Bug reportOct 14, 2026· 0:22· 0 views
ECharts 6.1.0: setTheme() clears merged series data — bar chart becomes empty after theme change
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Bug report— by SceneRecap AI
highchart theme/option merging logic (setTheme / setOption)
os: macOSbrowser: Chromium 151.0.7922.34version: ECharts 6.1.0viewport: 1280x720
Repro steps
- 1.Initialize ECharts instance using sequential setOption() calls (e.g., axes first, then series data merged)
- 2.Verify chart renders initial bar chart series data correctly (7 bars visible)
- 3.Click 'Set Dark Theme' button to trigger chart.setTheme('dark')
Expected
Calling setTheme('dark') re-themes the chart while preserving the merged series data and bars.
Actual
Calling setTheme('dark') clears the merged series data, rendering an empty black chart canvas with no bars.
Evidence
visualPrior to switching theme, 7 blue bars (120, 200, 150, etc.) are rendered with a status indicating '✓ Before setTheme — 7 bars visible'
visualAfter clicking 'Set Dark Theme', the chart turns dark but all 7 bars disappear, showing only axis labels and status '✕ After setTheme('dark') — bars gone, series data cleared (BUG)'
consoleConsole warning logged: 'After setTheme('dark'): {"hasData":false,"reason":"series[0] missing"} — BUG: series data lost — setOption merge discarded by setTheme()'
Issue markdown (copy-paste ready)
### Description
In ECharts 6.1.0, calling `setTheme('dark')` on an ECharts instance whose options were populated across multiple `setOption()` calls causes the merged `series` data to be discarded, resulting in an empty chart canvas without bars.
### Steps to Reproduce
1. Initialize an ECharts chart instance with two sequential `setOption()` calls (axes first, then series data).
2. Observe the initial bar chart rendering 7 bars.
3. Call `setTheme('dark')` (e.g., by clicking 'Set Dark Theme').
### Expected Result
The theme switches to dark mode while retaining the existing series data and visual bars.
### Actual Result
The theme switches to a dark background, but the series data is completely dropped (`series[0] missing`), leaving an empty chart canvas.
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