This is from the Economist article that Musk was tweeting about:

Well before it confirmed the latest missed production target, investors worried about the firm’s cash-burn rate in 2018. In addition to the $2bn or so of capital that may be required to expand production of the Model 3, Tesla has some $1.2bn in convertible debt maturing by early next year. On March 27th Moody’s, a credit-rating agency, downgraded Tesla’s debt, cautioning that the firm “will likely need to raise additional capital during the second half of 2019”. Jefferies, a bank, predicts that Tesla will need $2.5bn to $3bn this year.

The cited prediction by Moody’s was very close, apparently ("likely need to raise capital in the second half of 2019").