Once the upload is completed the page reloads and field is replaced by a thumbnail or a link depending what you were uploading.

Having said that I have also experienced problems uploading much larger files, although in my case I got an error about failing to load the page after the upload is supposedly completed, and just like you I have no idea whatever happened to the files. I guess that's the price to pay for browser-based uploads as opposed to better but less user-friendly protocols such as FTP.

I've been trying to upload "Kid Pix Studio Deluxe". However, when the upload is finished I get crude error messages like this one here for the screenshots:

{ "status": true, "data": "\x3cdiv id=\"edit-field-screenshot-0-ahah-wrapper\"\x3e\x3cdiv class=\"form-item\" id=\"edit-field-screenshot-0-wrapper\"\x3e\n \x3cdiv class=\"filefield-element clear-block\"\x3e\x3cdiv class=\"widget-preview\"\x3e\x3cdiv class=\"imagefield-preview\"\x3e\x3cimg src=\"http://macintoshgarden.org/sites/macintoshgarden.org/files/imagefield_thumbs/screenshots/kidpix_0.jpg\" title=\"kidpix.jpg\" /\x3e\x3c/div\x3e\x3c/div\x3e\x3cdiv class=\"widget-edit\"\x3e\x3cinput type=\"hidden\" name=\"field_screenshot[0][UPLOAD_IDENTIFIER]\" id=\"edit-field-screenshot-0-UPLOAD-IDENTIFIER\" value=\"f758377746d77b98843ad043cb4f6500\" class=\"filefield-progress\" /\x3e\n\x3cinput type=\"hidden\" name=\"field_screenshot[0][fid]\" id=\"edit-field-screenshot-0-fid\" value=\"4320\" /\x3e\n\x3cdiv class=\"form-item\" id=\"edit-field-screenshot-0-data-title-wrapper\"\x3e\n \x3clabel for=\"edit-field-screenshot-0-data-title\"\x3eTitle: \x3c/label\x3e\n \x3cinput type=\"text\" maxlength=\"500\" name=\"field_screenshot[0][data][title]\" id=\"edit-field-screenshot-0-data-title\" size=\"60\" value=\"\" class=\"form-text imagefield-text\" /\x3e\n \x3cdiv class=\"description\"\x3eThe title is used as a tool tip when the user hovers the mouse over the image.\x3c/div\x3e\n\x3c/div\x3e\n\x3cinput type=\"hidden\" name=\"field_screenshot[0][list]\" id=\"edit-field-screenshot-0-list\" value=\"1\" /\x3e\n\x3cinput type=\"submit\" name=\"field_screenshot_0_filefield_remove\" id=\"edit-field-screenshot-0-filefield-remove\" value=\"Remove\" class=\"form-submit\" /\x3e\n\x3c/div\x3e\x3c/div\x3e\n\x3c/div\x3e\n\x3c/div\x3e\x3cscript type=\"text/javascript\"\x3ejQuery.extend(Drupal.settings.ahah, { \"edit-field-screenshot-0-filefield-upload\": { \"url\": \"/filefield/ahah/app/field_screenshot/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-screenshot-0-ahah-wrapper\", \"selector\": \"#edit-field-screenshot-0-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/f758377746d77b98843ad043cb4f6500\", \"url\": \"/filefield/progress/f758377746d77b98843ad043cb4f6500\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-screenshot-0-filefield-remove\": { \"url\": \"/filefield/ahah/app/field_screenshot/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-screenshot-0-ahah-wrapper\", \"selector\": \"#edit-field-screenshot-0-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_screenshot_0_filefield_remove\": \"Remove\" } }, \"edit-field-screenshot-1-filefield-upload\": { \"url\": \"/filefield/ahah/app/field_screenshot/1\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-screenshot-1-ahah-wrapper\", \"selector\": \"#edit-field-screenshot-1-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/4434e5ea6ec7ff919e2cb4d81471313c\", \"url\": \"/filefield/progress/4434e5ea6ec7ff919e2cb4d81471313c\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-screenshot-1-filefield-remove\": { \"url\": \"/filefield/ahah/app/field_screenshot/1\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-screenshot-1-ahah-wrapper\", \"selector\": \"#edit-field-screenshot-1-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_screenshot_1_filefield_remove\": \"Remove\" } }, \"edit-field-file-0-filefield-upload\": { \"url\": \"/filefield/ahah/app/field_file/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-file-0-ahah-wrapper\", \"selector\": \"#edit-field-file-0-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/37f97bbb6df40ffd279bceffa09516c6\", \"url\": \"/filefield/progress/37f97bbb6df40ffd279bceffa09516c6\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-file-0-filefield-remove\": { \"url\": \"/filefield/ahah/app/field_file/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-file-0-ahah-wrapper\", \"selector\": \"#edit-field-file-0-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_file_0_filefield_remove\": \"Remove\" } }, \"edit-field-manual-0-filefield-upload\": { \"url\": \"/filefield/ahah/app/field_manual/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-manual-0-ahah-wrapper\", \"selector\": \"#edit-field-manual-0-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/483d493d0fc89e5377ee4c8937248bf0\", \"url\": \"/filefield/progress/483d493d0fc89e5377ee4c8937248bf0\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-manual-0-filefield-remove\": { \"url\": \"/filefield/ahah/app/field_manual/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-manual-0-ahah-wrapper\", \"selector\": \"#edit-field-manual-0-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_manual_0_filefield_remove\": \"Remove\" } }, \"edit-field-manual-1-filefield-upload\": { \"url\": \"/filefield/ahah/app/field_manual/1\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-manual-1-ahah-wrapper\", \"selector\": \"#edit-field-manual-1-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/9d499131f37680b327417d6f34d69950\", \"url\": \"/filefield/progress/9d499131f37680b327417d6f34d69950\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-manual-1-filefield-remove\": { \"url\": \"/filefield/ahah/app/field_manual/1\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-manual-1-ahah-wrapper\", \"selector\": \"#edit-field-manual-1-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_manual_1_filefield_remove\": \"Remove\" } } });\x3c/script\x3e" }

Any ideas? And did the file upload successfully? (at least it went up to 100%!)

It's a Safari problem, like mine, see
http://macintoshgarden.org/forum/no-longer-able-add-screenshots

Oh I see. I used Safari indeed. Thanks for the information IIGS User, i'll try another browser next time.

@Admins How about you put this piece of information on the upload page? I'm sure I won't be the last that tries to upload something - using Safari - and fails...

I didn't know what's changed between the times so that Safari no longer works with uploads.
I didn't change anything, the admins, seems, did also not change anything.