> ## Documentation Index > Fetch the complete documentation index at: https://docs.wuji.tech/llms.txt > Use this file to discover all available pages before exploring further. # Troubleshooting ## SDK installation fails 1. Confirm that Python is 3.8 or later 2. Update pip with `pip install --upgrade pip` 3. If you encounter compilation errors, try installing the pre-built wheel package ## Script throws an exception during execution | Exception Message | Cause | Resolution | | - | - | - | | `DeviceNotFound` | Device not discovered | Check physical connection and network | | `Disconnected` | Connection interrupted | Check cables, reconnect | | `ConnectionTimeout` | Connection timed out | Check network connection or increase timeout\_ms parameter | | `OperationTimeout` | Operation timed out | Increase timeout\_ms parameter or check device status | | `StreamClosed` | Subscription stream closed | Device may have disconnected, reconnect | | `SessionAlreadyExists` (C: `WUJI_STATUS_ERR_SESSION_EXISTS`) | A session for the same device already exists | If this process is already connected to the device, keep using the existing device connection object. If another session holds the device, wait for that session to disconnect or for the device heartbeat timeout, then reconnect | | Connecting to a Wuji Hand fails and names unresponsive joints | The hand isn't ready and some joints didn't answer | Check power and cabling, then reconnect once the joints are powered. The Python SDK and C SDK behave the same | | `WujiException` | Wuji Hand 2 write to `hand.mit_params()` (`kp` / `kd` both required non-negative), `hand.effort_limit()` (non-negative), or `joint_command` realtime publisher receives NaN / infinity / negative values | Filter invalid values before writing | | `WujiException` | Wuji Hand 2 write to `hand.effort_limit()` exceeds the ceiling the device currently allows, so the device rejects the write | Lower the value. Firmware sets the ceiling — read `effort_limit` back to confirm what's in effect | | `WujiException` | Calling Wuji Hand 2 `hand.joint(index)` with an index outside `0..=19` | Pass an integer from 0 through 19. The SDK raises `WujiException` before creating a joint handle | ## Data subscription has latency or frame drops * Check network bandwidth and latency (wired connection preferred over WiFi) * Reduce the number of simultaneously subscribed data streams * Ensure callback functions don't contain blocking operations * On Wuji Hand 2, subscribe to `hand.joint_diagnostics()` and read the frame-level `comm` summary to locate where frames go missing: `e2e_lost` is network loss, while `sdk_dropped` means your consumer is falling behind. For field definitions, see [Wuji Hand 2 SDK reference — Hand2CommSummary](https://docs.wuji.tech/docs/en/wuji-hand/latest/sdk-reference/diagnostics.md#hand2commsummary) ## SDK version is incompatible with the firmware * Check the [SDK release notes](https://docs.wuji.tech/docs/en/release-notes.md) for version compatibility * Keep SDK and firmware on the same minor version (e.g., both 0.6.x) ## After upgrading the SDK, `tactile_binary` or `tactile_residual` stops producing data The Wuji Glove tactile data layout now uses 24×31 (was 24×32). The SDK validates incoming frame size and the loaded contact calibration model against the new layout — if either still targets 24×32, the affected streams stop publishing to prevent misaligned output. To recover, upgrade the Wuji Glove firmware to a version that supports 24×31 and re-run tactile contact calibration under the new layout. See the [Wuji Glove tactile data reference](https://docs.wuji.tech/docs/en/wuji-glove/latest/sdk-data-reference/tactile.md) for details. ## Device Log Export ### Flash Log Export Disable the device and stop sending control commands before export. Wait for the export function to return and confirm that all concurrent exports for the device have finished before resuming control. See [Flash Log Export Precautions](https://docs.wuji.tech/docs/en/wuji-hand/latest/sdk-reference/diagnostics.md#flash-log-export-diagnostics). Wuji SDK provides the Wuji Hand 2 Flash log export API. After calling `export_flash_logs()`, the current thread waits until the SDK reads the device logs and writes the output file before the function returns a dictionary with `path` and `frames`. The output file uses JSONL format, with one JSON record per line. Wuji Hand 2 supports concurrent log exports from the same device while it is not being controlled. If the device doesn't support Flash log export, the call reports that the operation isn't supported: ```python theme={null} result = hand.export_flash_logs() print(result["path"], result["frames"]) ``` `path` is the output file path, and `frames` is the number of successfully decoded log frames. Pass a directory to `out_dir` to choose the destination. Without `out_dir`, the SDK writes to `~/.wuji/logs/flash___