Hi UncleCheese,

I have checked now another complete new installation, the only modules dataobject, swfupload, image-gallery. The directory image-gallery was created but the album is not possible.
I have now a trace:

[Warning] mkdir(): Unable to access /<..>/httpdocs/assets/image-gallery/New-ImageGalleryPage-8/1/
POST /admin/EditForm/field/Albums/AddForm?ctf[Albums][start]=0&ctf[Albums][per_page]=10&ctf[Albums][showall]=0&ctf[Albums][sort]=SortOrder&ctf[Albums][sort_dir]=DESC&ctf[Albums][search]=&ctf[Albums][filter]=

Line 30 in /<..>/httpdocs/sapphire/filesystem/Folder.php
Source

21
22       foreach($parts as $part) {
23          $item = DataObject::get_one("Folder", "Name = '$part' AND ParentID = $parentID");
24          if(!$item) {
25             $item = new Folder();
26             $item->ParentID = $parentID;
27             $item->Name = $part;
28             $item->Title = $part;
29             $item->write();
30             if(!file_exists($item->getFullPath())) mkdir($item->getFullPath(),Filesystem::$folder_create_mask);
31          }
32          $parentID = $item->ID;
33       }
34       return $item;
35    }
36    

Trace

* mkdir(/<..>/httpdocs/assets/image-gallery/New-ImageGalleryPage-8/1/,1533)
Line 30 of Folder.php
* Folder::findOrMake(image-gallery/New-ImageGalleryPage-8/1)
Line 63 of ImageGalleryAlbum.php
* ImageGalleryAlbum->onBeforeWrite()
Line 783 of DataObject.php
* DataObject->write()
Line 245 of DataObjectManager.php
* DataObjectManager->saveComplexTableField(Array,DataObjectManager_Popup,HTTPRequest)
Line 241 of Form.php
* Form->httpSubmission(HTTPRequest)
Line 129 of RequestHandler.php
* RequestHandler->handleRequest(HTTPRequest)
Line 143 of RequestHandler.php
* RequestHandler->handleRequest(HTTPRequest)
Line 143 of RequestHandler.php
* RequestHandler->handleRequest(HTTPRequest)
Line 143 of RequestHandler.php
* RequestHandler->handleRequest(HTTPRequest)
Line 119 of Controller.php
* Controller->handleRequest(HTTPRequest)
Line 277 of Director.php
* Director::handleRequest(HTTPRequest,Session)
Line 121 of Director.php
* Director::direct(/admin/EditForm/field/Albums/AddForm)
Line 118 of main.php

I haven't payed attention. It seems that I have changed the safe mode. Now it works correctly with safe mode off.