# Will the NextSeq 500/550 Control Software prevent run setup with read lengths fewer than 25 cycles?

This type of run configuration is possible in standalone mode, PrepTab, and Local Run Manager. However, BaseSpace will not generate FASTQ files for reads that are less than 25 cycles.

Illumina does not recommended insert reads lengths shorter than 25 cycles.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #2565), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000002565%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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