Sorry, that post could not be updated

I'm receiving a "Sorry, that post could not be updated" error on the test site of a website. It's working fine locally. Debug says:

Debug Message
SELECT u.*, r.* FROM perch2_users u, perch2_user_roles r WHERE u.roleID=r.roleID AND u.userEnabled=1 AND u.userID=1 AND u.userHash='d03e5789bc345e2f2f8487e2646dc033' LIMIT 1
UPDATE perch2_users SET userHash='2de79039c29d1ee743847861879e66c7' WHERE userID='1'
SELECT p.privKey FROM perch2_user_privileges p
SELECT * FROM (SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=1 OR userID=0 ORDER BY userID DESC) AS settings GROUP BY settingID
SELECT * FROM perch2_blog_authors WHERE authorEmail='phil@18two.co.uk' LIMIT 1
SELECT * FROM perch2_blog_sections ORDER BY sectionTitle ASC
Using template: /templates/blog/post.html
Dynamic fields:
Array
(
    [postTitle] => Amazing weekend
    [image] => 
    [theme] => dark
    [excerpt] => Array
        (
            [raw] => Words
            [processed] => 
Words

        )

    [postImage] => 
    [postDescHTML] => Array
        (
            [raw] => Words
            [processed] => 
Words

        )

    [authorSlug] => 
    [postDateTime] => 2015-07-17 14:03:00
)
INSERT INTO perch2_blog_posts(postTags,postStatus,postTemplate,authorID,sectionID,postAllowComments,postDescRaw,postDescHTML,postTitle,postDateTime,postDynamicFields,postSlug) VALUES('','Published','post.html','12','4','0','Words','<p>Words</p>','Amazing weekend','2015-07-17 14:03:00','{\"image\":null,\"theme\":\"dark\",\"excerpt\":{\"raw\":\"Words\",\"processed\":\"<p>Words<\\/p>\"},\"postImage\":null,\"authorSlug\":null}','2015-07-17-amazing-weekend')
SELECT * FROM perch2_blog_posts WHERE postID=1
SELECT COUNT(*) AS qty, c.catID FROM perch2_blog_index i, perch2_categories c, perch2_blog_posts p WHERE i.indexValue=c.catPath AND i.indexKey='_category' AND i.itemKey='postID' AND i.itemID=p.postID AND p.postStatus='Published' AND p.postDateTime<='2015-07-17 14:03:00' GROUP BY i.indexValue
DELETE FROM perch2_category_counts WHERE countType='blog.post'
SELECT authorID, COUNT(*) AS qty FROM perch2_blog_posts WHERE postStatus='Published' AND postDateTime<='2015-07-17 14:03:00' GROUP BY authorID
UPDATE perch2_blog_authors SET authorPostCount=0
UPDATE perch2_blog_authors SET authorPostCount='7' WHERE authorID=2 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='2' WHERE authorID=3 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='5' WHERE authorID=4 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='5' WHERE authorID=5 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='5' WHERE authorID=6 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='1' WHERE authorID=7 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='1' WHERE authorID=8 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='2' WHERE authorID=9 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='3' WHERE authorID=10 LIMIT 1
UPDATE perch2_blog_authors SET authorPostCount='5' WHERE authorID=12 LIMIT 1
SELECT c.sectionID, COUNT(p.postID) AS qty FROM perch2_blog_sections c, perch2_blog_posts p WHERE c.sectionID=p.sectionID AND p.postStatus='Published' AND p.postDateTime<='2015-07-17 14:03:00' GROUP BY c.sectionID ORDER BY c.sectionTitle ASC
UPDATE perch2_blog_sections SET sectionPostCount=0
UPDATE perch2_blog_sections SET sectionPostCount='3' WHERE sectionID='4' LIMIT 1
UPDATE perch2_blog_sections SET sectionPostCount='22' WHERE sectionID='1' LIMIT 1
UPDATE perch2_blog_sections SET sectionPostCount='14' WHERE sectionID='3' LIMIT 1
UPDATE perch2_blog_sections SET sectionPostCount='4' WHERE sectionID='0' LIMIT 1
UPDATE perch2_blog_sections SET sectionPostCount='4' WHERE sectionID='2' LIMIT 1
SELECT COUNT(*) FROM perch2_blog_comments WHERE commentStatus='PENDING'
SELECT * FROM perch2_blog_authors ORDER BY authorFamilyName, authorGivenName ASC
Queries: 51
Memory: 4.7165