# Troubleshooting Bit Error on the NextSeq 500/550 and MiniSeq

* The following error occurs when launching the Control Software or during the pre-run check of the imaging system on the NextSeq 500/550 or MiniSeq.
* This error can result from a transient communication issue or an issue with the optical system.
* Typically the error can be resolved by power cycling the instrument.
* **Note**: Bit rate error is resolved in instruments upgraded to NextSeq 500/550 Control Software (NCS) v4.0.1.

**Error Language**: Bit error check failed Originally caused by: DMA Read failed with return code 32. ![](/files/aL5eNexMSkOCjpQf5Hid)

**Figure 1.** "Bit error check failed Originally caused by: DMA Read failed with return code 32"

**Troubleshooting steps:**

1. Open **Control Panel** → **Device Manager** and verify *Illumina DMA Driver* under Data Acquisition is loaded or not.

* *Illumina DMA Driver* is present, power cycle the instrument once and restart the run.
* *Illumina DMA Driver* is NOT present, power cycle the instrument once. Login to **sbsadmin** and open the **Control Panel** → **Device Manager** to verify if *Illumina DMA Driver* under Data Acquisition is now loaded or not. If *Illumina DMA Driver* is present now, restart the run.

2. If Illumina DMA Driver is still not present, power cycle the instrument a second time. Login to **sbsadmin**, and open the **Control Panel** → **Device Manager** to check if *Illumina DMA Driver* under Data Acquisition is now loaded or not. Note that sometimes the second power cycle is required.

* If “Illumina DMA Driver” is present now, restart the run.
* If “Illumina DMA Driver” is still **not** present, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html#/united-states/technical-support).

**To power cycle the instrument:**

1. From the home screen, select **Manage Instrument**.
2. Select **System Shutdown Options**.
3. Select **Shut Down** to close the control software and turn off the instrument.
4. When the instrument is off, wait 3-5 minutes and turn the instrument back on by pressing the power button in the front.
5. Allow the control software initialize.

**Additional resources:**

* [NextSeq 500 and NextSeq 550 Sequencing System Guide](https://sapac.support.illumina.com/downloads/nextseq-500-550-systems-product-documentation.html)
* [MiniSeq System Guide](https://support.illumina.com/downloads/miniseq-system-guide-1000000002695.html)
* For further information, search for Knowledge Base article [How to Perform a NextSeq 500/550 Power Cycle](https://knowledge.illumina.com/instrumentation/nextseq-500-550/instrumentation-nextseq-500-550-reference_material-list/000001972).

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #6684), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000006684%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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