Running a query such as the following, followed by a SELECT FOUND_ROWS() will result in an error, and the found rows not being returned.
SELECT DISTINCT SQL_CALC_FOUND_ROWS wp_users.ID FROM wp_users WHERE 1....
results in this error:
Attempted SELECT FOUND_ROWS() without prior SQL_CALC_FOUND_ROWS.
For an example of code that can trigger this, see WordPress/wporg-mu-plugins#412
Running a query such as the following, followed by a
SELECT FOUND_ROWS()will result in an error, and the found rows not being returned.results in this error:
For an example of code that can trigger this, see WordPress/wporg-mu-plugins#412