Troubleshooting Object Reference error on NextSeq 500/550

An "Object reference not set to an instance of an object" is a Windows Framework error that can occur for a number of reasons.

It is often caused by communication issues between instrument subsystems or an issue with the network connection. These can appear at any time (during setup, pre-run checks, sequencing runs, post-run washes, etc.). If during a run, this may or may not affect the run performance.

Troubleshooting steps:

• If the error occurs during run setup or post run wash (not during a run):

  1. Power cycle the NextSeq 500/550.

  2. If system initializes without issue, proceed with run setup or wash.

• If the error occurs during the run:

  1. After run completion, confirm run performance was not affected by error.

  2. Power cycle the NextSeq 500/550.

  3. If system initializes without issue, proceed with normal use.

• If run was affected/stopped:

  1. Contact Illumina Technical Support.

For further information, search for Knowledge Base articles How to Perform a NextSeq 500/550 Power Cycle and Specifications for the NextSeq 500/550.

For any feedback or questions regarding this article (Illumina Knowledge Article #7435), contact Illumina Technical Support [email protected].