How do Bible scholars view the accuracy and reliability of the Aleppo Codex? Background information: Circa A.D. 930, sages and scribes completed the writing of the Aleppo Codex, the first definitive Tanakh, or Hebrew Bible. From Tiberias, the codex was taken to Jerusalem. But Crusaders laid waste to the city in 1099, slaughtering its inhabitants and taking the codex.  The Aleppo Codex, the oldest Hebrew Bible in existence today, is so named because it was housed for half a millennium in Aleppo, Syria.  Between the 1947 riots in Aleppo, Syria, and the codex’s arrival in Israel in 1957, almost 200 pages of the Aleppo Codex went missing.

I have been asked specifically about the Aleppo Codex and if it is considered to be reliable, and find myself completely out of my depth. Is there any information on the Aleppo Codes to be found on the Christianity Stack Exchange?  I do not yet know how to navigate my way around this web site and could do with some help.
The Aleppo Codex is a bound manuscript of the Hebrew Bible, written by scribes called Masoretes in Tiberias, Israel, around 930 C.E.  They surfaced in Aleppo, Syria, sometime in the second half of the 15th century; preserved nearly intact in a synagogue for centuries, until the 20th century.

The Aleppo Codex belongs to a large “family” of Masoretic manuscripts (MS), which contain vocalization, cantillation marks, and Masoretic annotations.  One of the best known manuscripts closely related to the Aleppo Codex is MS Leningrad.  Some editions of the Bible are based on MS Leningrad, the best known being the latest editions of Biblia Hebraica.  

The Aleppo Codex is considered to be the most authoritative copy of the Hebrew Bible. The Dead Sea Scrolls—which are a thousand years older than the Aleppo Codex and which contain all of Isaiah and some of the Psalms from the Hebrew Bible –  lack vowels.  The Aleppo Codex features both vowel markings and marginal notations. 

Three important editions of the Bible based on the Aleppo Codex, are: 1) The Breuer edition.  2) The edition of the Hebrew University Bible Project.  3) The Keter edition of Miqraot Gedolot, published by Bar-Ilan University Press.
Significantly, both the New International Version and the New Living Translation of the Bible base their Old Testament translations on the Masoretic Text of the Biblia Hebraica.

I assume that since the Masoretic Text and the Biblia Hebraica are of significance to modern English translations of the Bible, and since the Aleppo Codex is considered by many to be the most authoritative copy of the Hebrew Bible, being part of the family of Masoretic MS, then the Aleppo Codex is viewed as important and trustworthy.

Some controversy surrounds the history of the Aleppo Codex and some parts of the Hebrew text are still missing, but the pedigree of the Aleppo Codex seems to be accepted by reputable Bible scholars.  I hasten to add, however, that this is only what I have culled from the articles in the links below. Please study them for yourself and form your own conclusions.

https://www.biblicalarchaeology.org/daily/biblical-topics/hebrew-bible/the-aleppo-codex/

http://www.aleppocodex.org/links/7.html