> For the complete documentation index, see [llms.txt](https://knowledge.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.illumina.com/instrumentation/general/instrumentation-general-troubleshooting-list/000009020.md).
# Troubleshooting "Failed to communicate with RTA after 4 attempts" on the MiniSeq or NextSeq 500/550
**Background**
Users may encounter the error "Failed to communicate with RTA after 4 attempts" during a sequencing run, which may cause the run to terminate prematurely. Occasionally, this may occur before the reagent cartridge is pierced, which would allow for it to be reused in a new run setup.
**Troubleshooting steps**:
1. Ensure there is no antivirus software, firewall or proxy system blocking the connection between the Control Software and Real-Time Analysis (RTA), which operates on port 8081
2. Confirm that Region Format in Windows is set to "English (United States)". Any other region may use different formats that are incompatible with Illumina software. This can be done via **Control Panel** > **Region** > **Formats** tab > **Format** (dropdown menu).
3. Power Cycle the system. For power cycling instructions, reference the articles below depending on the instrument:
1. [How to Power Cycle the NextSeq 500/550](/instrumentation/general/instrumentation-general-reference_material-list/000001972.md)
2. [How to Power Cycle the MiniSeq](/instrumentation/miniseq/instrumentation-miniseq-reference_material-list/000002010.md)
4. If the issue persists, 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 #9020), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000009020%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
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