Restrictions and limitations when you sync SharePoint libraries through OneDrive for Business

Restrictions and limitations when you sync SharePoint libraries through OneDrive for Business

Number of items that can be synced
•    You can sync up to 20,000 items in your OneDrive for Business library, this includes folders and files.
•    You can sync up to 5,000 items in a SharePoint library, this includes folders and files.
•    In any library (OneDrive for Business/Sharepoint), you can sync files of up to 2 gigabytes (GB).
•    Storage available on your OneDrive for Business : 1 Terabyte

Invalid characters & filenames

Folder Names and File Names
•    Do not use: ” # % & * : ? / { | } ~
•    Do not use the period character consecutively in     the middle of a file name.  For example, “file..name.docx”     is invalid.
•    You cannot start a file name with the period character
•    File names cannot be longer than 128 characters
•    You cannot use the period character at the end of a file name
•    Many other symbols are not recommended such as     $^()-_=+[]`! (other international currency symbols and international symbols should be avoided in site names, but some are more acceptable in file names. Ascii is preferred when possible.

In addition, file names and folder names may not end with: (Many of these are international symbols)
.files, _files , -Dateien , _fichiers , _bestanden , _file ,_archivos ,-filer,_tiedostot ,_pliki ,_soubory ,_elemei ,   _arquivos ,_dosyalar ,_datoteke ,_fitxers,_failid,_fails ,_bylos ,_fajlovi,_fitxategiak

Invalid file types
You cannot upload OneNote files, or files with a *.tmp or *.ds_store extension. Additionally, you cannot upload desktop.ini, thumbs.db, or ehthumbs.db.

Consult the following articles for more information:

Restrictions and limitations when you sync SharePoint libraries to your computer through OneDrive for Business

SharePoint Online: software boundaries and limits