The most current Manual on Uniform Traffic Control Devices was published in 2009. In 2017, the Federal Highway Administration (FHWA) published a nine-page list of known errors in that document. However, the FHWA cautions "The FHWA intends to correct these errors via a future rulemaking action. This list of known errors is provided solely for the information of MUTCD users and does not constitute official changes to the MUTCD at this time."
The PDF of the known errors can be accessed at https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/2009r1r2mutcd_errors.pdf
Additionally, the MUTCD instituted new required sizes for regulatory signs that went into effect December 22, 2013. They are listed in a chart that can be accessed at http://mutcd.info/mutcd-2009-standard-regulatory-sign-sizes/