The error itself "mkdir(): Too Many Links" is not very useful, but I'll translate it into plain English.
It means you've reached the filesystem's limit of how many directories can be created in a single directory.
In this case for ext3 the limit is 32000 and it was exceeded.
What's the solution?
The simple solution is to move those directories into more subdirectories possibly sorting them by date, alphabet or numerically. This can be a pain and also may not be practical if those files are expected in their current location unless you make a symlink to the original location (eg. if a database is relying on that info), you'll either have to modify each entry in the database, alter your code etc.. and neither is desirable for production systems.
Is there another solution?
Yes ext4, I migrated the VPS to an ext4 based host and I believe there's no directory limit at all anymore with ext4.
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