Is there a limit of max. number of files in external hard drive folder?

I have a FAT32 external hard drive where I keep backups downloaded from webserver. I have a directory with 30 subdirectories. One of the subdirectories contains 21381 files and when I try to copy more files into this directory I get 0x80070052 error. However,it's possible to copy one more file in this directory (only one) if I make it's name shorter (8 characters instead of 22 as it's original name).

How do I solve this problem? Now I can not synchronize external hard disk files with server files which is very important for me.

I don't think FAT32 has a file limit that's specific to one folder, but the total number of files on a FAT32 volume is limited to 268,173,300 with 32kb clusters. This number decreases the smaller your clusters are, because the filesystem can only address so many clusters. So eventually if you use really small clusters, you will run out of clusters.

However, a quick google for your specific error message yields this page; http://www.quickonlinetips.com/archives/2007/09/how-to-fix-error-0x80070052-on-usb-flash-drives/ which says that the problem was having too many files in the root directory of the volume (i.e. not in any subfolder). So you might want to try removing some files or folders from the root folder if possible. I'm not sure if this will help you.

Of course, the other option would be to not use FAT32. exfat and NTFS are both suitable.