I've had that recently, and it took me half a day to debug - turns out
there was a tiddler* containing "malformed" wiki markup*, which caused
this exception when being rendered.
So if you open the imported tiddlers one after another, you should be
able to identify the culprit.
HTH.
-- F.
I've created a page on the community wiki:
http://www.tiddlywiki.org/wiki/URIError:_Malformed_URI_Sequence
Feel free to create a list of problematic characters there.
> debug tiddlywiki to to allow more characters in the title without error
It's already on the list of things we need to look into.
The more information we have (ideally, reproducible test cases), the
easier it will be for us to identify the problem.
-- F.