# Troubleshooting GenomeStudio "Error writing data beyond end of sample"

#### **Description**

During the final step of GenomeStudio Genotyping project creation, the following window with "Error - writing data beyond end of sample" message appears.

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-b443835d3187c165b31e063946d715ef8cdeffcf%2Fimage1.png?alt=media)

The subsequent window "The Project can not be created. No valid samples were loaded." message appears and GenomeStudio is unable to create a project.

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-3224854cf4492c28d5dab15b46f24745eef597a3%2Fimage2.png?alt=media)

#### **Resolution**

This error can occur when both IDAT files and GTC files are found in the same repository folder.\
To resolve the issue, transfer the GTC files to a separate folder so that only the IDATs remain in the scan folder.

When re-creating the project, GenomeStudio should be able to access only one type of source file (IDATs).

For additional information, see Illumina Knowledge article [Can Genotype Call (GTC) files be used as input for GenomeStudio?](https://knowledge.illumina.com/microarray/general/microarray-general-reference_material-list/000005917).

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #3031), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000005917%20-%20Microarray%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |