TYPO3 Core

I decided to explore more in depth.
The error during manual install is from class.em_terconnection.php:

00148 function decodeExchangeData($str) {
00149 $parts = explode(':',$str,3);
00150 if ($parts¹=='gzcompress') {
00151 if (function_exists('gzuncompress')) {
00152 $parts² = gzuncompress($parts²);
00153 } else return 'Decoding Error: No decompressor available for compressed content. gzcompress()/gzuncompress() functions are not available!';
00154 }
00155 if (md5($parts²) == $parts⁰) {
00156 $output = unserialize($parts²);
00157 if (is_array($output)) {
00158 return array($output,'');
00159 } else return 'Error: Content could not be unserialized to an array. Strange (since MD5 hashes match!)';
00160 } else return 'Error: MD5 mismatch. Maybe the extension file was downloaded and saved as a text file by the browser and thereby corrupted!? (Always select "All" filetype when saving extensions)';
00161 }

Therefore, the problem is with gzuncompress function (that reports "data error") or with variable $str ($parts = explode(':',$str,3);). That causes the final error messages.

What do you think it can be? I have no idea for now.

Any more information on this? Does this problem still occur? This was probably some php / network problem?!

I finally resolved the issue. My hosting provider blocked outgoing connections, so fopen did not work. After some discussion the hosting provider opened the connection, and the issue was gone.

It would be nice to see the error description in more details. I tried to figure it out for a month or so.

your problem as mentioned by yourself:
"My hosting provider blocked outgoing connections, so fopen did not work."

the error message when clicking on retrieve update:
"The mirror list was not updated, it could not be fetched from http://repositories.typo3.org/mirrors.xml.gz. Possible reasons: network problems, allow_url_fopen is off, curl is not enabled in Install tool."

your suggestion:
"It would be nice to see the error description in more details."

In my opinion, the error message IS descriptive enough. I'm going to close the issue.