# Troubleshooting Reagent Valve errors on the MiSeq
Users may encounter a Reagent Valve error during runs or washes.
* This error can include the phrase “ReagentValve ReadResponse”, or state “The reagent valve will not respond”.
In either case, it is referring to the valve that selects which reagent will be pumped across the flow cell. If the error occurs mid-run, the run will stop and will not be able to be resumed. This error is caused by either communications issues on the instrument or by a faulty Reagent Valve.
**Troubleshooting steps:**
1. Power cycle the MiSeq. Further guidance may be found in the Illumina Knowledge article [How to Shut Down or Power Cycle the MiSeq](https://knowledge.illumina.com/instrumentation/miseq/instrumentation-miseq-reference_material-list/000001894).
2. If there are no issues with MiSeq Control Software (MCS) re-initialization, perform a wash to make sure the fluidics are operating normally.
3. If MCS fails to initialize or the wash does not complete successfully, contact [Illumina Technical Support.](https://www.illumina.com/company/contact-us.html#/)
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| *For any feedback or questions regarding this article (Illumina Knowledge Article #1458), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000001458%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
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