Alright, I think I found a solution to this but requires some work. Unfortunately, I couldn\'t get the geeklog backup to work, and silly me didnt think of doing it manually, so I crossed my fingers and upgraded, running into this \'is_default\' problem. Note: I am upgrading from 1.3.7 to 1.3.8.
Warning! Before you do any of this, be sure that you are confident working with mysql, and that you don\'t have a backup that you could use to re-install. Also, read through all the details and all the steps first, because some may not apply, depending on how much of the your upgrade processed the first time around before the error. AND, do this as a last resort, only after doing what Dirk said, and if you don\'t have a database backup to restore.
So here goes...
In the geeklog database you will need to make the following changes, under the assumption that your prefix is set to \"gl_\".
1) Drop the field \'is_default\' from the table \'gl_topics\'.
2) Drop the field \'pwrequestid\' from the table \'gl_users\'.
3) Drop the field \'lastlogin\' from the table \'gl_userinfo\'.
4) Drop the field \'emailfromuser\' from the table \'gl_userprefs\'.
5) Drop the field \'showonline\' from the table \'gl_userprefs\'.
6) Drop the table \'gl_speedlimit\'.
7) Create the table \'gl_commentspeedlimit\'.
7.1) You will need a field, so just create an empty test field.
8) Create the table \'gl_submitspeedlimit\'.
8.1) Again, you will need a field, create an empty one.
9) Now, if you are using one of Geeklog\'s theme\'s, such as XSilver, then you should be able to re-install the upgrade to 1.3.8, and get the success page. If you are using a custom theme, then copy the file adminoption_off.thtml from the folder /layout/XSilver/ to your theme folder (/layout/theme_name/).
Quick Note here: If you are using a custom theme, you may not need to go through the first 8 steps listed above. In order to test this, in the config file, set the default theme to XSilver, and turn off the option for users to change themes. These settings are for $_CONF[\'theme\'] and $_CONF[\'allow_user_themes\']. Once you do that, open up the browser and check the site. You may still get some template errors with a \"Halted\" message, which I will address (step 11) and is okay. So if you see your site with the errors, this is good, just copy the file as described in step 9 and skip the next step (10). If not, then you probably need to do steps 1-8 first.
10) If you did steps 1-9, then go ahead and try to install the upgrade. You should hopefully get the success page, as I did. If not, then there is no hope. Just kidding... I didn\'t encounter any errors in this step, but if you do, then you might have to find another solution.
11) Again, if you are using a custom theme, there are some files that have been added to Geeklog\'s theme\'s and may not be in yours. When designing my theme I used gameserver for my template architecture as a starting point, because it had different templates for the left and right blocks. I am pretty sure though that you can copy the following files/folders from any of the Geeklog theme. The files are located in /layout/theme_name/ and are:
adminoption_off.thtml (Same file from step 9).
admin/database/* (The entire folder).
preferenes/* (The entire folder).
Note: I\'m not sure if you need all the files (someone else might know, Dirk?), but I know that I needed some of them and just copied them all rather than QA\'ing my site after copying one file at a time (way to time consuming). Also, if you already have these files in your theme, don\'t copy them, or overwrite them.
That should be it. I ran through my entire site real quick, and from what I could tell, all the updates were there, and nothing was broken, with no loss of content in the database. Again, make sure some of the steps apply to you before doing them. Hope this helps and good luck.