Narrative:

I set up the mcdu and briefed the first officer (first officer) it would be a flaps 4 departure. Being his leg; I had him give me the rest of the takeoff brief. We ran the 'before start to the line checklist;' boarded; closed; pushed; and ran the 'before start below the line checklist.' on this check; first officer called flaps 2 required; selected; and indicated. Being that was what was selected; I repeated back '2 verified.' this was the 1st chance to catch that flaps 4 needed to be selected.I had ran the ACARS for flaps 4 data and inputted those takeoff speeds into the mcdu; but flaps 2 were still selected at this point and is what was selected for takeoff in the mcdu. On the taxi as part of my taxi flow; is the second chance I had to catch the mistake of flaps 2 selected instead of flaps 4. Next we ran the taxi check; and then being number 1 for takeoff; first officer started on his pre-takeoff checks. It was here we got a takeoff config ok. I held short of the runway; looked down at my notes and saw my reminder that we needed to be flaps 4. I told first officer; and he selected flaps 4. We were then cleared for takeoff.we ran the before takeoff check and lined up on the runway. I gave first officer the controls. As he pushed the thrust levers forward; we got a 'no take off - flaps.' we immediately throttled back and contacted the tower telling them we needed to exit the runway to check something. We were basically given two right turns to taxi back to [the] runway. We figured out we had the right flap setting selected; the right ACARS speeds for flaps 4 inputted; but had not set flaps 4 in the mcdu. We corrected our mistake; ran all appropriate checklists again; received clearance for takeoff; and continued on our way.complacency; lack of CRM; and overall missing attention to detail led to this incident. A checklist is useless if you do not actually check what you are supposed to. Moving forward; anytime something (ie flaps; data; etc) needs to be verified- I will take the time to point and look right at that of which needs to be verified and checked. I will encourage my coworkers to do the same and that if something doesn't look right- speak up.

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Original NASA ASRS Text

Title: EMB-175 Captain reported that they rejected takeoff due to a misconfigured flap position.

Narrative: I set up the MCDU and briefed the First Officer (FO) it would be a Flaps 4 departure. Being his leg; I had him give me the rest of the Takeoff brief. We ran the 'before start to the line checklist;' boarded; closed; pushed; and ran the 'before start below the line checklist.' On this check; FO called Flaps 2 required; selected; and indicated. Being that was what was selected; I repeated back '2 verified.' This was the 1st chance to catch that flaps 4 needed to be selected.I had ran the ACARS for flaps 4 data and inputted those takeoff speeds into the MCDU; but Flaps 2 were still selected at this point and is what was selected for takeoff in the MCDU. On the taxi as part of my Taxi flow; is the second chance I had to catch the mistake of Flaps 2 selected instead of Flaps 4. Next we ran the taxi check; and then being number 1 for takeoff; FO started on his pre-takeoff checks. It was here we got a Takeoff config ok. I held short of the runway; looked down at my notes and saw my reminder that we needed to be Flaps 4. I told FO; and he selected Flaps 4. We were then cleared for Takeoff.We ran the before takeoff check and lined up on the runway. I gave FO the controls. As he pushed the Thrust levers forward; we got a 'No Take Off - Flaps.' We immediately throttled back and contacted the tower telling them we needed to exit the runway to check something. We were basically given two right turns to taxi back to [the] runway. We figured out we had the right Flap setting selected; the right ACARS speeds for Flaps 4 inputted; but had not set Flaps 4 in the MCDU. We corrected our mistake; ran all appropriate checklists again; received clearance for takeoff; and continued on our way.Complacency; lack of CRM; and overall missing attention to detail led to this incident. A checklist is useless if you do not actually check what you are supposed to. Moving forward; anytime something (ie Flaps; data; etc) needs to be verified- I will take the time to point and look right at that of which needs to be verified and checked. I will encourage my coworkers to do the same and that if something doesn't look right- speak up.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.