I've been using CAML queries to do list updates for quite some time, but recently they've stopped working, and I have no idea why. Even an extremely simple query seems to be failing. For example the following CAML should set the document with an ID of 1 to have the name "Walrus",
<?xml version="1.0" encoding="UTF-8"?>
<ows:Batch OnError="Return">
<Method ID="1">
<SetList>a16802b6-9ccc-4652-832e-609b584431bb</SetList>
<SetVar Name="Cmd">Save</SetVar>
<SetVar Name="ID">1</SetVar>
<SetVar Name="urn:schemas-microsoft-com:office:office#Name">walrus</SetVar>
</Method>
</ows:Batch>
When I sent this via Web.ProcessBatchData, I get an error "One or more field types are not installed properly, go to list settings to delete these field types".
I create Site Columns and Content Types via a Visual Studio solution. It seems that when I add a new content type into an already existing hierarchy (e.g. trying to change the parent content type of existing content types), I run into all kinds of problems.
If anyone has any advice on how to better diagnose or fix whatever this issue is I'd be very appreciative. If only the VS designers for Content Types and Site Columns weren't so bad...
Update: The error "One or more field types..." was only occurring during my testing because I was trying to update a field that couldn't be updated. The CAML Queries are broken, but in fact I get no error message (an error code of 0).