Why Does Warning 30906 Appear at Startup?

Hi,
Our PLC is 4PPC30.043F-22B with X20BR7300+Seveal I/O cards.
I’ve check the logger and found warning 30906 every startup.
Could anyone explain why this warning comes up?

AS version 4.12
AR version H4.93
4PPCC30 hardware version 1.1.3.0
BR7300 hardware version 1.8.0.0

Automation help indicate

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