As to the question of when the consonantal skeleton finally reached closure and the corpus no longer was open to further editions—that is, the date of the Qurʾān’s codification and establishment of the ne varietur text—most Islamologists now agree that this occurred by at least the late first/seventh century (for this consensus, see Jonathan E. Brockopp, “Islamic Origins and Incidental Normativity,” Journal of the American Academy of Religion 84 [2016], p. 34). However, there are currently two competing dates in modern scholarship: [1] middle of the first/seventh century (650s CE) under ʿUthmān b. ʿAffān (r. 23–35 AH/644–56 CE); or [2] between the beginning and the end of the second half of the first/seventh century (c. 685–705 CE) under the Umayyad caliph ʿAbd al-Malik b. Marwān (r. 65–85 AH/704–704 CE) and his patron, al-Ḥajjāj b. Yūsuf al-Thaqafī (r. 75–96 AH/694–713 CE).
For the first possibility, see Estelle Whelan, “Forgotten Witness: Evidence for the Early Codification of the Qurʾān,” Journal of the American Oriental Society 118 (1998), pp. 1–14; Michael Cook, “A Koranic Codex Inherited by Mālik from His Grandfather,” Graeco-Arabica 7–8 (2000), pp. 93–105; id., “The Stemma of the Regional Codices of the Koran,” Graeco-Arabica 9–10 (2004), pp. 89–104; Behnam Sadeghi and Uwe Bergmann, “The Codex of a Companion of the Prophet and the Qurʾān of the Prophet,” Arabica 57 (2010), pp. 343–436; id., & Mohsen Goudarzi, “Ṣanʿāʾ 1 and the Origins of the Qurʾān,” Der Islam 87 (2012), pp. 1–129; Yasin Dutton, “An Umayyad Fragment of the Qurʾan and its Dating,” Journal of Qurʾanic Studies 9 (2007), pp. 57–87; Gregor Schoeler, “The Codification of the Qurʾan: A Comment of the Hypothesis of Burton and Wansbrough,” in Angelika Neuwirth, Nicolai Sinai & Michael Marx (eds.), The Qurʾān in Context: Historical and Literary Investigations into the Qurʾānic Milieu, Leiden, 2010, pp. 779–94; Nicolai Sinai, “When did the consonantal skeleton of the Quran reach closure? Part I,” Bulletin of the School of Oriental and African Studies 77 (2014), pp. 273–92; id., “When did the consonantal skeleton of the Quran reach closure? Part II,” Bulletin of the School of Oriental and African Studies 77 (2014), pp. 509–21 (Sinai’s two-part article is the status quaestionis on the matter); Herbert Berg, “The collection and canonization of the Qurʾān,” in id. (ed.), Routledge Handbook on Early Islam, London, 2017, pp. 37–48; Marijn van Putten (forthcoming).
For the second, see Paul Casanova, Mohammed et la fin du monde, Paris, 1911, pp. 103–142 and 162; Alphonse Mingana, “The Transmission of the Ḳurʾān,” Journal of the Manchester Egyptian and Oriental Society 5 (1915–1916), pp. 25–47; Patricia Crone & Michael Cook, Hagarism: The Making of the Islamic World, Cambridge, 1977, p. 17f. (both have since retracted and now accept the ‘first possibility’; Patrica Crone, The Qurʾānic Pagans and Related Matters: Collected Studies in Three Volumes, ed. Hanna Siurua, Leiden-Boston, 2016, p. xiii; and for Michael Cook, see his 2000 and 2004 articles in Graeco-Arabica above); Patricia Crone, “Two Legal Problems Bearing on the Early History of the Qurʾān,” Jerusalem Studies in Arabic and Islam 18 (1994), pp. 1–37; Yehuda Nevo, “Towards a Prehistory of Islam,” Jerusalem Studies in Arabic and Islam 17 (1994), pp. 108–41; Stephen J. Shoemaker, “Christmas in the Qurʾān: The Qurʾānic Account of Jesus’ Nativity and Palestinian Local Tradition,” Jerusalem Studies in Arabic and Islam 28 (2003), pp. 11–39; id., The Death of a Prophet: The End of Muhammad’s Life and the Beginnings of Islam, Philadelphia, 2012, pp. 136–58; David S. Powers, Muḥammad Is Not the Father of Any of Your Men: The Making of the Last Prophet, Philadelphia, 2009, pp. 155–96 and 227–33; id., “From Nuzi to Medina: Q. 4:12b, Revisited,” in Ilan Peled (ed.), Structures of Power: Law and Gender Across the Ancient Near East and Beyond, Chicago, 2017, pp. 181–201; Alfred-Luis de Prémare, Les fondations de l’islam. Entre écriture et histoire, Paris, 2002, pp. 278–322. Arabic translation: Taʾsīs al-Islām: bayna al-kitāba wa-l-tārīkh, trans. ʿĪsā al-Muḥāsibī, Beirut, 2009, pp. 313–359; id., Aux origines du Coran: Questions d’hier, approaches d’aujourd’hui, Paris, 2004; id., “ʿAbd al-Malik b. Marwān et le processus de constitution du Coran”, in Karl-Heinz Ohlig & Gerd-Rüdiger Puin, Die dunklen Anfänge: Neue Forschungen zur Entstehung und frühen Geschichte des Islam, Berlin, 2005, pp. 179–210. English translation: “ʿAbd al-Malik b. Marwān and the Process of the Qurʾān’s Composition,” in Karl-Heinz Ohlig & Gerd-Rüdiger Puin, The Hidden Origins of Islam: New Research into Its Early History, Amherst, pp. 181–221; Chase Robinson, ʿAbd al-Malik, Oxford, 2005, pp. 100–4; Guillaume Dye, “Pourquoi et comment se fait un texte canonique: quelques réflexions sue l’histoire de Coran,” in Christian Brouwer, Guillaume Dye & Anja van Rompaey (eds.), Hérésies: une construction d’identités religieuses, Bruxelles, 2015, pp. 55–104; see also Michael Cook, The Koran: A Very Short Introduction, Oxford, 2000, pp. 119–22.
Considering evidence from an array of disciplines and methods—including numismatics, epigraphy, philology, paleography, codicology, art history, and radiocarbon dating—suggestions placing the ne varietur text sometime in the late second/eighth and/or early third/ninth century (à la Wansbrough, for instance; Quranic Studies: Sources and Methods of Scriptural Interpretation, Oxford, 1977, pp. 44–5) are henceforth obsolete, irrespective of whether one prefers the first or second possibility (see the references above). Cf. Andrew Rippin, “Foreword”, in John Wansbrough (auth.), Quranic Studies: Sources and Methods of Scriptural Interpretation, Amherst, 2004, pp. xiv–xviii. My understanding is that the late Prof. Rippin (d. 2016) – notwithstanding certain limitations – has since aligned his views with the broader scholarly community in that the Qurʾān’s codification took place by at least the late first/seventh century. Jonathan E. Brockopp, “Islamic Origins and Incidental Normativity,” Journal of the American Academy of Religion 84 (2016), p. 34. Another ‘Wansbroughian revisionist’, Hebert Berg, has also conceded that Wansbrough’s claim concerning the ne varietur text needs modification, proposing a mid-Umayyad codification date (i.e. ‘second possibility’). Herbert Berg, “The Needle in the Haystack: Islamic Origins and the Nature of the Early Sources,” in Carlos A. Segovia & Basil Lourié (eds.), The Coming of the Comforter: When, Where, and Whom? Studies on the Rise of Islam and Various Other Topics in Memory of John Wansbrough, Piscataway, 2012, p. 272, note 3. Several years later, Berg espoused some skepticism concerning the mid-Umayyad codification hypothesis, writing that despite its appeal, it “raises more issues than it solves”. Herbert Berg, “The collection and canonization of the Qurʾān,” in id. (ed.), Routledge Handbook on Early Islam, London, 2017, p. 45.
Please see the fourth paragraph for the answer to your question.