Core

Also applies to 4.5

It seems to happen only when there is already an existing translation.

If I clear the typo3temp folder first, it works without a problem.

Side note: I'm testing on a server with a slow connection.

I experience this issue in 4.5.6 as well.

I have the same problem in 4.6.0

It still exists in 4.5.10 in case someone was wondering.

So I did a little digging myself and here is what I found.

The core problem here is the tx_em_Tools_Unzip class.
tx_em_Connection_Ter::updateTranslation will call tx_em_Tools::unzip
tx_em_Tools::unzip sees that I did not supply a path to the unzip utility and decides to use the internal class tx_em_Tools_Unzip.

It will now assume that the return value of tx_em_Tools_Unzip::unzip is an array when it completes successfully. This assumption seems to be false.
This results in tx_em_Tools::unzip returning false and tx_em_Connection_Ter::updateTranslation returning FALSE. Thus, it appears as if the process failed.

So a workaround is just to supply $GLOBALS['TYPO3_CONF_VARS']['BE']['unzip_path'] with a path to the unzip utility and everything works great again.

Thanks Oliver for diggin'.

The workaround is pretty nice, still I'd like to see that fixed properly.
Do have a patch suggestions, which you could push to gerrit?

Sadly, I have no patch yet. But I was looking a bit more into the tx_em_Tools_Unzip class and noticed that it logs errors. So I had a look at the error that causes it to behave as observed. For the extensions I have installed in the test environment I get these errors:

ARCHIVE_ZIP_ERR_BAD_FORMAT (-10) : Fail to find the right signature
ARCHIVE_ZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature

/powermail-l10n-de.zip NoName (1) :

So, back to the errors. To my understanding, they are generated at the end of the extraction process (in _readEndCentralDir). But there's a little too much magic going on for me to tell if there is a problem in the code or if the zip file is actually damaged. In which case it might be a problem with the downloading of the file maybe.

I'm pretty confident that the issue is with the tx_em_Tools_Unzip class. It is based on an older version of pclzip.lib.php. I looked at the latest version of that library at http://www.phpconcept.net/pclzip and compared both versions.
pclzip has two modifications in the _readEndCentralDir method (turns out one of the returned errors is simply not valid). Now all "Fail to find the right signature" errors are gone (yay). Sadly, most archives produce the "Unable to find End of Central Dir Record signature" error.

Any news on this one?