If you look at that error message, it's trying to change entry to entry_content with a column type of "TEXT". I can see in the older upgrade routines why this is happening and will submit a fix.
In the mean time, you would need to edit applications/blog/setup/upg_40000/queries.json to change
"17": {
"method": "changeColumn",
"params": [
"blog_entries",
"entry",
{
"name": "entry_content",
"type": "TEXT",
to
"17": {
"method": "changeColumn",
"params": [
"blog_entries",
"entry",
{
"name": "entry_content",
"type": "MEDIUMTEXT",