This is a summary of various sticky postings taken from the cpg1.3.x support board (most of them originally posted by hyperion) that are valid for cpg1.4.x as well:
When troubleshooting uploads in CPG 1.4, you are advised to change the upload settings in the Groups console to 'Single uploads only' and to activate 'Debug mode' in the Config console. Changing this setting negates some of the error masking done in the multiple upload setting. This will allow you to access more detailed error messages. This is being explained in the docs that come with cpg1.4.x:
http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#upload_troubleMake sure that you have read the documentation before asking any support requests.
FIRST AND FOREMOST: CHECK YOUR PERMISSIONS ON THE /ALBUMS, /ALBUMS/USERPICS, AND /ALBUMS/EDIT DIRECTORIES. ALL SHOULD BE 777 OR 755. If you don't know what we mean when we write 777 or 755, you need to do a Google search on UNIX file permissions. Windows has a similar set of file permissions. You can usually set these permissions using your FTP client.
For those of you who skim over statements written in large letters, I will repeat to try to get your attention:
YES, WE ARE WRITING ABOUT SOMETHING THAT COULD APPLY TO YOU.
WE REPEAT -- CHECK YOUR PERMISSIONS ON THE /ALBUMS, /ALBUMS/USERPICS, AND /ALBUMS/EDIT DIRECTORIES. ALL SHOULD BE 777 OR 755.
YES, WE WANT YOU TO CHECK THE PERMISSIONS OF EACH FOLDER EVEN IF YOU THINK YOU HAVE ALREADY DONE THIS. YES, WE MEAN IT. There's a section in the docs that tries to explain permissions:
http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#permissions
Please keep in mind that HTTP uploads are limited by the restrictions placed upon them in PHP's configuration.
Things to check:
1. max_input_time- 60 seconds is the default time limit for uploading files.
This time limit includes the time it takes for the files to upload, so if you exceed this limit, the file will not even parse, and the browser will not get a response. You can workaround this by trying to upload smaller or fewer files, or you can try uploading over broadband. The best solution, of course, is to increase the time limit to something more in line with your needs.
2. upload_max_filesize - 2MB is the default limit for individual files.
3. post_max_size - 8MB is the default limit for post requests.
4. memory_limit - 8MB is the default size.
5. PHP's LimitRequestBody - 512KB default limit. (mainly an issue on Redhat/Apache systems. Found in /etc/http/conf.d)
In general, upload_max_filesize < post_max_size < memory_limit in order for uploads to function properly. Coppermine may warn you if a file exceeds upload_max_filesize, but it cannot warn you if the total size of all the files exceeds the post limit or the memory limit.
6. file_uploads - This determines whether or not PHP will allow file uploads. It must be set to 'On'.
7. upload_tmp_dir - This specifies the temporary directory where PHP stores uploaded files.
The most common issue caused by this setting is an open_basedir warning. In this situation, your server administrator has restricted the files that PHP can work with to a certain directory. If he does not create and specify a temporary directory within the open_basedir restriction, PHP will attempt to use the OS temporary directory, and it will be rebuffed by the open_basedir restriction.
8. allow_fopen_url - This controls PHP's ability to read files using URL/URIs. If it is disabled, Coppermine will not be able to upload from URLs.
Some notes about the different types of upload mechanisms available in CPG 1.3:
Multiple HTTP uploads are designed to handle a small number of files, and have been capped at 10. Therefore, they are not really suited for large numbers of files unless you have control over your php.ini configuration.
If you are looking to upload in excess of 15 or 20 files at a time, you should consider the batch add process or the XP_Publisher utility. Each has its own drawbacks and advantages.
The batch add process is fast, but it puts quite a load on the server and may experience timeouts. The XP Publisher utility is slower, but it limits the load on the server. Also, it avoids many of the pitfalls caused by the php.ini configuration by uploading each file in the set as an individual post request.