diff --git a/micropip/errors.py b/micropip/errors.py
new file mode 100644
index 00000000..0ace81fd
--- /dev/null
+++ b/micropip/errors.py
@@ -0,0 +1,24 @@
+"""
+A module to define micropip custom Exceptions.
+"""
+
+
+class UnsupportedContentTypeError(Exception):
+    """raise when selecting a parser for current index
+
+    This is raise if the current content type is not recognized.
+    """
+
+
+class NoCompatibleWheelError(Exception):
+    """
+    This is raised when a package is found but have no wheel compatible with
+    current pyodide.
+    """
+
+
+class PackageNotFoundOnAnyIndexError(Exception):
+    """
+    This is raised if current package was not found on any of the currently
+    listed index.
+    """
diff --git a/micropip/package_index.py b/micropip/package_index.py
index f7cf02a6..afd36b1e 100644
--- a/micropip/package_index.py
+++ b/micropip/package_index.py
@@ -13,6 +13,7 @@
 
 from ._compat import HttpStatusError, fetch_string_and_headers
 from ._utils import is_package_compatible, parse_version
+from .errors import PackageNotFoundOnAnyIndexError, UnsupportedContentTypeError
 from .externals.mousebender.simple import from_project_details_html
 from .wheelinfo import WheelInfo
 
@@ -234,7 +235,9 @@ def _select_parser(content_type: str, pkgname: str) -> Callable[[str], ProjectIn
         ):
             return partial(ProjectInfo.from_simple_html_api, pkgname=pkgname)
         case _:
-            raise ValueError(f"Unsupported content type: {content_type}")
+            raise UnsupportedContentTypeError(
+                f"Unsupported content type: {content_type}"
+            )
 
 
 async def query_package(
@@ -296,14 +299,11 @@ async def query_package(
             raise
 
         content_type = headers.get("content-type", "").lower()
-        try:
-            parser = _select_parser(content_type, name)
-        except ValueError as e:
-            raise ValueError(f"Error trying to decode url: {url}") from e
+        parser = _select_parser(content_type, name)
         return parser(metadata)
     else:
-        raise ValueError(
-            f"Can't fetch metadata for '{name}'. "
+        raise PackageNotFoundOnAnyIndexError(
+            f"Can't fetch metadata for {name!r}. "
             "Please make sure you have entered a correct package name "
             "and correctly specified index_urls (if you changed them)."
         )
diff --git a/micropip/transaction.py b/micropip/transaction.py
index 9d64a72a..5223af3d 100644
--- a/micropip/transaction.py
+++ b/micropip/transaction.py
@@ -13,8 +13,9 @@
 from ._compat import REPODATA_PACKAGES
 from ._utils import best_compatible_tag_index, check_compatible
 from .constants import FAQ_URLS
+from .errors import NoCompatibleWheelError
 from .package import PackageMetadata
-from .package_index import ProjectInfo
+from .package_index import PackageNotFoundOnAnyIndexError, ProjectInfo
 from .wheelinfo import WheelInfo
 
 logger = logging.getLogger("micropip")
@@ -153,12 +154,23 @@ def eval_marker(e: dict[str, str]) -> bool:
             else:
                 try:
                     await self._add_requirement_from_package_index(req)
-                except ValueError:
-                    logger.debug(
-                        "Transaction: package %r not found in index, will search lock file",
+                except PackageNotFoundOnAnyIndexError:
+                    logger.warning(
+                        "Transaction: package %r was not found in any index, "
+                        "falling back to pyodide lock file",
+                        req,
+                    )
+                    # This is most likely an error, and it's likely we should
+                    # hard fail here, but the legacy behavior was to ignore
+                    # errors.
+                    if not self._add_requirement_from_pyodide_lock(req):
+                        raise
+                except NoCompatibleWheelError:
+                    logger.warning(
+                        "Transaction: no compatible wheels for package %r was "
+                        "found falling back to pyodide lock file",
                         req,
                     )
-
                     # If the requirement is not found in package index,
                     # we still have a chance to find it from pyodide lockfile.
                     if not self._add_requirement_from_pyodide_lock(req):
@@ -167,7 +179,7 @@ def eval_marker(e: dict[str, str]) -> bool:
                         )
 
                         raise
-        except ValueError:
+        except (NoCompatibleWheelError, PackageNotFoundOnAnyIndexError):
             self.failed.append(req)
             if not self.keep_going:
                 raise
@@ -292,7 +304,7 @@ def find_wheel(metadata: ProjectInfo, req: Requirement) -> WheelInfo:
         if best_wheel is not None:
             return wheel
 
-    raise ValueError(
+    raise NoCompatibleWheelError(
         f"Can't find a pure Python 3 wheel for '{req}'.\n"
         f"See: {FAQ_URLS['cant_find_wheel']}\n"
         "You can use `await micropip.install(..., keep_going=True)` "