Soldering female header connector to PCB - neighbor pins some how got connected

Other Hardware General Electronics
7

Thank you guys for advices.

I use this flux https://www.amazon.com/gp/product/B000G33PAI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

and this soldering iron

I will try to clean PCBs I created and avoid using FLUX for PCBs in the future.