The English majors over at Dell provided me with this error message provided by a PowerEdge 2950.

CPU2 Status: Processor sensors for CPU2, IERR was deasserted

I've Googled it, random forum posts aren't providing me with a clear answer.

It's also apparently not a word: http://dictionary.reference.com/browse/deassert?s=t

I can guess the meaning. Assert:

to state with assurance, confidence, or force

Okay. So the negative of that. The state of lack-of-confidence? What is this error message trying to tell me? Memory errors were grouped with this one: is it trying to say that IERR for CPU2 should be set, but is not? That the current system state is SNAFU but CPU2 sees everything as fine?

  • a signal is asserted when its logical state is set (forced) to true, deasserted when it's set to false or unknown - note that some signals are true with low voltage and some with high. See electronics.stackexchange.com/questions/33302/… for more information.
    – user359077
    Jun 5, 2016 at 23:50

3 Answers 3


My best translation would be 'Stopped signaling'.

Say I have an alarm button. I can push this button to send a signal. Then I release the button to stop sending that signal. Replace 'push' with 'assert' and 'release' with 'de-assert' and you get the meaning.


I'm not sure where this term started gaining usage in regards to error conditions, but I've seen it with several vendors.

Basically, an error condition is present if it is "asserted". Then if at some point the error condition ceases to exist, a message is logged that said condition is deasserted.


Further to ErikA's answer...

This terminology carries "up" from digital logic. When you say that a digital signal is "asserted" it's the same as saying it represents a binary value of 1. De-asserted is the same as binary 0.

In your case, the message means that signal IERR was set to 0, i.e. turned off.

  • There are signals which are, by definition, asserted low, i.e. get asserted when they get to 0 (low) voltage level - SD card's SS line for example. Their names are usually underscored. It makes little sense to speak of "binary value" in this context, because it's way too ambiguous. I agree that IERR was turned off - yet it doesn't have to be turned off by setting it low - it may as well get turned off by setting it to logical high. Also, sometimes you deassert by simply leaving a logical state undefined. As such, I find your answer severly lacking and misleading.
    – user359077
    Jun 5, 2016 at 23:53

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