# How to Resolve "sma\_air\_a/b was not present in dictionary" Errors During Pre Run Checks on the NovaSeq X Plus

**Background**

During Pre-Run Checks, the instrument performs several tests to verify that the instrument is ready for sequencing. Any issues during this process will result in Error messages that can assist in identify the issue and resolving it. This article describes how to resolve issues with the System Thermal check that occurs during the Dry Checks section at the start of the Pre-Run Checks.

**Error Message**

"The given key 'sma\_air\_a/b' was not present in the dictionary"

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-8b148fc6a045c08a13bb7270e32c2f16427babbf%2Fimage1.png?alt=media\&token=06868423-704f-4957-ac12-b47ce416195c)

**Troubleshooting Actions**

**Important**: No consumables are marked as used if this error presents during the Pre-Run Checks and consumables can be used in a follow up sequencing run.

To resolve this issue, see the following steps:

1. Select the **Return to Start** button to exit the Pre-Run Checks
2. Close the NovaSeq X Series Control Software:
   1. Select the **instrument icon** in the bottom-middle of the **Home** screen to open the global navigation menu.
   2. Select **Settings**.
   3. Select **Exit Software**.
3. Restart the NovaSeq X Series Control Software:
   1. From the Linux Operating System (OS), select the **Activities** menu in the top-left corner.
   2. Select the icon for the **NovaSeq X Series Control Software**.
4. Once the Control Software has initialized, proceed with restarting run setup.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #8539), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000008539%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |