Add two more items to troubleshooting doc (#263)

docs/troubleshooting.md

@@ -5,3 +5,11 @@ Encountering an error, mystery, or other unexplained oddity? Open a ticket on th
 ## I get an error like `TypeError: ConfiguredBaseModel.__init_subclass__() takes no keyword arguments`
 
 This can happen if you have installed a version of the Pydantic package older than version 2 and/or if you're using a schema generated for Pydantic v1. Versions of OntoGPT of v0.3.3 and above should prevent this from happening, but if you're still seeing the error, then running `make` again may fix it.
+
+## I get an error like `urllib.error.HTTPError: HTTP Error 404: Not Found`
+
+There are a variety of reasons why this may happen, but one cause is if your schema specifies an annotator which does not exist. If the stack trace of the error includes the `get_adapter` method from `oaklib`, then this is a likely cause, and you may want to verify that all annotators are accessible to OAK.
+
+## I get a lot of warnings like `WARNING:root:Could not find any mappings for ...` and I don't get the expected identifiers in my extracted object
+
+Verify that the `id_prefixes` you specify in your schema correspond to those provided by the annotator. If your annotator is `sqlite:obo:hp`, for example, the prefix will be `HP` rather than `HPO`.