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My Macbook Pro ran into a problem and reported Error: -50. I cannot open applications such as Chrome, Word, and others. I cannot download content or move content to the trash because it says the disk is full, even though it still shows 80Gb of free storage. The Ram is free and I cannot run ClamXav to see if it is a virus. Disk Utility verifies the disk but the permissions have all changed and cannot be repaired. Some permissions errors include "user differs on private/var/at, should be 0 user is 1"as well as various others. I cant even see/open external drives I connect. Any idea how to solve this problem?

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Finder error -50 when moving files from external NTFS hard disk (2012-08-11) has an accepted answer. Whilst that question is about NTFS, it's useful to consider the origins of -50 and the range of situations in which the error may present. – Graham Perrin Apr 20 '13 at 7:41

-50 is a file system error: "Error in user parameter list" (see

What OS X version are you on? or Will reinstalling Lion erase all my documents and applications? maybe helpful.

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+1 for drawing attention to HT1618 (outdated and archived but still, a useful point of reference for many things). Whilst the error relates to the file system, it does does not necessarily indicate a problem at the file system level. – Graham Perrin Apr 20 '13 at 9:09

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