On 2013–01–25 Devendra Ghate wrote:

> Just upgraded context installation( to 2013.01.24 16:47),
> corrected my MWE and I am still getting exactly the same error.

You're right, it fails here, too. The message got lost in between
all the tikz log output. On my machine I get:

Package tikz: Error! I did not find the tikz library 'external'. I looked for files named tikzlibraryexternal.code.tex and pgflibraryexternal.code.tex, but neither could be found in the current texmf trees..

And tikz is right with that. There is no such file in the
distribution. Either the name of this module changed or the file is
missing in the distribution, I guess.

The pgfplots module ships with a file called

/pgfplots/oldpgfcompatib/pgfplotsoldpgfsupp_tikzlibraryexternal.code.tex

this seems to be the file in question. However, the name
“oldpgfcompatib” insinuates that this module might be deprecated.
Maybe Mojca knows more details about this issue.

Marco