This line has been renamed to "Computation Error: unexplained difference" to better explain what it means.

It normally means one of the following:

• You have added a Custom Account Type to Odoo and have not modified the definition of the Cash Flow Report to include/exclude transactions in this account.

• You have created Accounts without Tagging them in a way that the Cash Flow report can find them (or have tagged them incorrectly).

To resolve this error, check your Chart and Tags and use the default Chart as a guide.  Also review the definition of the Cash Flow Statement to understand how the lines are computed.