How most of the mainstream media, in the US at least, nauseatingly wrote about the WMD theory which was the main stated reason for the US to go to 2003 Iraq war. That region is still reeling with consequences of that war and not to speak about trillions of $$ spent, hundreds of thousands of lives lost, and nuclear contamination and so on and on.
It's really hard to blame the media for the Iraq war, the Bush II administration wanted to go to war, particularly in Iraq and were happy to beat the drums as loud as necessary to get the public's backing. Who can ever forget Powell lying in front of Congress, but that what was necessary to seal the deal and the media was more than happy to report what they learned.
It was the media's fault but not Bush and Cheney's? I don't remember where I got the information that led me to join the largest antiwar protests in history in 2003 but a lot of us knew Bush was lying because of the media.
I didn't say it was media's fault alone, but their share of responsibility is a large one. How else would the Bush administration have gained the support of the public? By transmitting their falsehoods through popular private media corporations such as CNN. And the media were all too happy to lap up the narrative fed by the administration without bothering to investigate deeper.
Not investigating deeper is different than outright lying for propaganda. "The President Said X" is newsworthy though maybe lazy reporting. If X is a lie it's on the president.