SharePoint 2007 Enterprise, SP2.
I am getting a strange error (found in the ULS logs, Google reports no hits on the message itself) when trying to upload a page with a webpart preloaded in a zone:
An unexpected error has been encountered in this Web Part. Error: Unable to parse markup correctly. It is likely that the markup should be in Visual Studio Attribute format, but the given markup is in XML Format., DesignText: <VPCQWP:ComponentLandingCQWP runat="server" id="CL_CQWP" />
This webpart derives from the ContentByQueryWebPart class, and sets a number of web-context sensitive properties.
This is the whole of the WebPartZone, and yes - the TagPrefix is registered properly at the top of the page:
<WebPartPages:WebPartZone runat="server" FrameType="TitleBarOnly" ID="TopLeft" Title="Top Left">
<ZoneTemplate>
<VPCQWP:ComponentLandingCQWP runat="server" id="CL_CQWP"></VPCQWP:ComponentLandingCQWP>
</ZoneTemplate>
</WebPartPages:WebPartZone>
The crazy part is if I clear this web part out from the zone, upload the page, and then add the web part back in thru the web UI, it works, no problem. What am I missing here?