When I sold my first apartment in Finland, there was a line of six sales that needed to go through in order for everyone to be able to pay for the next. At the same time, we had to sell ours to get hold of the deposit needed for our next. We were lucky though, as essentially we were downsizing in value of the purchase, and then renovating. We were well in the black after the renovation, meaning we had a fair amount of collateral in the second apartment. Then, when we sold that, we sold at a substantial profit, so we had a significant deposit for the house we are in now, bought just before lockdowns. Get the timing wrong however, and it would have been very different.