Ralf Rangnick has revealed the Manchester United board ignored his pleas to sign a new striker in January.
Man Utd have struggled for consistency all season, and their striker ranks took a blow during the transfer window.
Mason Greenwood was suspended by the club as he faced a personal legal issue, while Anthony Martial had already been loaned to Sevilla.
That prompted Rangnick to recommend the club dipped into the transfer market, only for it to fall on deaf ears.
"I was informed about the issue around Mason Greenwood and Anthony Martial had already left, and then I was aware that within four days we had some strikers missing and that it might make sense (to buy)," Rangnick said.
"We were still in three competitions - the FA Cup, the Champions League, at the time we were fourth in the league…
"I spoke to the board and told them, 'Shouldn't we at least speak and analyse and find if we can at least get a player, on loan or a permanent deal?'
"In the end the answer was no. The answer was no, maybe they didn't want to do any winter (business). It doesn't matter, the answer was no."
Later asked if they would have been realistic targets, Rangnick replied: "I don't know.
"But as I said, maybe we should have at least internally discussed it. It might be necessary and important…
"I still believe we should have at least tried. If we would have found and been able within 48 hours (to sign a player), it would have been short notice but still, 48 hours is 48 hours.
"It might have been at least worth to try and internally discuss it. We didn't. It was not done."
Manchester united went on to disappoint in the second half of the season and saw Champions League qualification slip from their grasp, and Rangnick believes the primary cause for that was a lack of goals.
"Obviously there were some problems that the team already had at the end of November and the first couple of months, at least until the end of January, we were improving," Rangnick said.
"Then in that international break we lost, including Edinson Cavani, three players long-term. We lost them, three strikers. Then we had problems to score goals and find our balance. This is what happened."