Abdul'baha explained this in detail;
45: EXPLANATION OF THE VERSE OF THE KITÁB-I-AQDAS, “THERE IS NO PARTNER FOR HIM WHO IS THE DAYSPRING OF REVELATION IN HIS MOST GREAT INFALLIBILITY”
"
It is said in the holy verse: “There is no partner for Him Who is the Dayspring of Revelation in His Most Great Infallibility. He is, in truth, the exponent of ‘God doeth whatsoever He willeth’ in the kingdom of creation. Indeed the Almighty hath exclusively reserved this station for Himself and to none is given a share in this sublime and highly exalted distinction.”
Know that infallibility is of two kinds: essential infallibility and acquired infallibility....Essential infallibility is peculiar to the supreme Manifestation.....
....But acquired infallibility is not a natural necessity; on the contrary, it is a ray of the bounty of infallibility which shines from the Sun of Reality upon hearts, and grants a share and portion of itself to souls. Although these souls have not essential infallibility, still they are under the protection of God—that is to say, God preserves them from error. Thus many of the holy beings who were not dawning-points of the Most Great Infallibility, were yet kept and preserved from error under the shadow of the protection and guardianship of God, for they were the mediators of grace between God and men. If God did not protect them from error, their error would cause believing souls to fall into error, and thus the foundation of the Religion of God would be overturned, which would not be fitting nor worthy of God........
:...To epitomize: essential infallibility belongs especially to the supreme Manifestations, and acquired infallibility is granted to every holy soul. For instance, the Universal House of Justice, if it be established under the necessary conditions—with members elected from all the people—that House of Justice will be under the protection and the unerring guidance of God. If that House of Justice shall decide unanimously, or by a majority, upon any question not mentioned in the Book, that decision and command will be guarded from mistake. Now the members of the House of Justice have not, individually, essential infallibility; but the body of the House of Justice is under the protection and unerring guidance of God: this is called conferred infallibility.
Briefly, it is said that the “Dayspring of Revelation” is the manifestation of these words, “He doeth whatsoever He willeth”; this condition is peculiar to that Holy Being, and others have no share of this essential perfection. That is to say, that as the supreme Manifestations certainly possess essential infallibility, therefore whatever emanates from Them is identical with the truth, and conformable to reality. They are not under the shadow of the former laws. Whatever They say is the word of God, and whatever They perform is an upright action. No believer has any right to criticize; his condition must be one of absolute submission, for the Manifestation arises with perfect wisdom—so that whatever the supreme Manifestation says and does is absolute wisdom, and is in accordance with reality..."
Regards Tony