diff --git a/hgext/convert/__init__.py b/hgext/convert/__init__.py
--- a/hgext/convert/__init__.py
+++ b/hgext/convert/__init__.py
@@ -85,6 +85,10 @@ def convert(ui, src, dest=None, revmapfi
     Mercurial Source
     -----------------
 
+    --config convert.hg.ignoreerrors=False (boolean) 
+        ignore integrity errors when reading. Use it to fix Mercurial
+        repositories with missing revlogs, by converting from and to
+        Mercurial.
     --config convert.hg.saverev=True          (boolean)
         allow target to preserve source revision ID
     --config convert.hg.startrev=0            (hg revision identifier)
diff --git a/hgext/convert/hg.py b/hgext/convert/hg.py
--- a/hgext/convert/hg.py
+++ b/hgext/convert/hg.py
@@ -192,6 +192,8 @@ class mercurial_sink(converter_sink):
 class mercurial_source(converter_source):
     def __init__(self, ui, path, rev=None):
         converter_source.__init__(self, ui, path, rev)
+        self.ignoreerrors = ui.configbool('convert', 'hg.ignoreerrors', False)
+        self.ignored = {}
         self.saverev = ui.configbool('convert', 'hg.saverev', True)
         try:
             self.repo = hg.repository(self.ui, path)
@@ -253,23 +255,35 @@ class mercurial_source(converter_source)
         parents = self.parents(ctx)
         if not parents:
             files = util.sort(ctx.manifest().keys())
-            return [(f, rev) for f in files], {}
+            return [(f, rev) for f in files if f not in self.ignored], {}
         if self._changescache and self._changescache[0] == rev:
             m, a, r = self._changescache[1]
         else:
             m, a, r = self.repo.status(parents[0], ctx.node())[:3]
-        changes = [(name, rev) for name in m + a + r]
-        return util.sort(changes), self.getcopies(ctx, m + a)
+        # getcopies() detects missing revlogs early, run it before
+        # filtering the changes.
+        copies = self.getcopies(ctx, m + a)
+        changes = [(name, rev) for name in m + a + r 
+                   if name not in self.ignored]
+        return util.sort(changes), copies
 
     def getcopies(self, ctx, files):
         copies = {}
         for name in files:
+            if name in self.ignored:
+                continue
             try:
-                copynode = ctx.filectx(name).renamed()[0]
-                if self.keep(copynode):
-                    copies[name] = copynode
+                copysource, copynode = ctx.filectx(name).renamed()
+                if copysource in self.ignored or not self.keep(copynode):
+                    continue
+                copies[name] = copysource
             except TypeError:
                 pass
+            except revlog.LookupError, e:
+                if not self.ignoreerrors:
+                    raise
+                self.ignored[name] = 1
+                self.ui.warn(_('ignoring: %s\n') % e)
         return copies
 
     def getcommit(self, rev):
@@ -297,6 +311,7 @@ class mercurial_source(converter_source)
         else:
             i = i or 0
             changes = self.repo.status(parents[i], ctx.node())[:3]
+        changes = [[f for f in l if f not in self.ignored] for l in changes]
 
         if i == 0:
             self._changescache = (rev, changes)
diff --git a/tests/test-convert-hg-source b/tests/test-convert-hg-source
--- a/tests/test-convert-hg-source
+++ b/tests/test-convert-hg-source
@@ -36,5 +36,34 @@ cd ..
 hg convert --datesort orig new 2>&1 | grep -v 'subversion python bindings could not be loaded'
 cd new
 hg out ../orig
+cd ..
+
+echo % init broken repository
+hg init broken
+cd broken
+echo a >> a
+echo b >> b
+hg ci -qAm init
+echo a >> a
+echo b >> b
+hg copy b c
+hg ci -qAm changeall
+hg up -qC 0
+echo bc >> b
+hg ci -m changebagain
+HGMERGE=internal:local hg -q merge
+hg ci -m merge
+hg mv b d
+hg ci -m moveb
+echo % break it
+rm .hg/store/data/b.*
+cd ..
+
+hg --config convert.hg.ignoreerrors=True convert broken fixed
+hg -R fixed verify
+echo '% manifest -r 0'
+hg -R fixed manifest -r 0
+echo '% manifest -r tip'
+hg -R fixed manifest -r tip
 
 true
diff --git a/tests/test-convert-hg-source.out b/tests/test-convert-hg-source.out
--- a/tests/test-convert-hg-source.out
+++ b/tests/test-convert-hg-source.out
@@ -20,3 +20,27 @@ 0 mark baz executable
 comparing with ../orig
 searching for changes
 no changes found
+% init broken repository
+created new head
+% break it
+initializing destination fixed repository
+scanning source...
+sorting...
+converting...
+4 init
+3 changebagain
+ignoring: data/b.i@4b3c32ced4f8: no match found
+2 changeall
+1 merge
+0 moveb
+checking changesets
+checking manifests
+crosschecking files in changesets and manifests
+checking files
+3 files, 5 changesets, 5 total revisions
+% manifest -r 0
+a
+% manifest -r tip
+a
+c
+d
diff --git a/tests/test-convert.out b/tests/test-convert.out
--- a/tests/test-convert.out
+++ b/tests/test-convert.out
@@ -72,6 +72,10 @@ Convert a foreign SCM repository to a Me
     Mercurial Source
     -----------------
 
+    --config convert.hg.ignoreerrors=False (boolean) 
+        ignore integrity errors when reading. Use it to fix Mercurial
+        repositories with missing revlogs, by converting from and to
+        Mercurial.
     --config convert.hg.saverev=True          (boolean)
         allow target to preserve source revision ID
     --config convert.hg.startrev=0            (hg revision identifier)