diff --git a/changelog/unreleased/issue-3556 b/changelog/unreleased/issue-3556
new file mode 100644
index 000000000..9d1d6d5c3
--- /dev/null
+++ b/changelog/unreleased/issue-3556
@@ -0,0 +1,8 @@
+Bugfix: Fix hang with Backblaze B2 if SSL certificate authority error
+
+If a request failed with an SSL unknown certificate authority error, the
+B2 backend retried indefinitely and restic would appear to hang.
+It now returns the error and restic fails with an error message.
+
+https://github.com/restic/restic/issues/3556
+https://github.com/restic/restic/issues/2355
diff --git a/go.mod b/go.mod
index 27ccba5de..8920927bd 100644
--- a/go.mod
+++ b/go.mod
@@ -15,7 +15,7 @@ require (
 	github.com/google/go-cmp v0.5.6
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/juju/ratelimit v1.0.1
-	github.com/kurin/blazer v0.5.3
+	github.com/kurin/blazer v0.5.4-0.20211030221322-ba894c124ac6
 	github.com/minio/minio-go/v7 v7.0.14
 	github.com/minio/sha256-simd v1.0.0
 	github.com/ncw/swift/v2 v2.0.0
diff --git a/go.sum b/go.sum
index 52d25cae0..76a3bd10b 100644
--- a/go.sum
+++ b/go.sum
@@ -243,8 +243,8 @@ github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORN
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
-github.com/kurin/blazer v0.5.3 h1:SAgYv0TKU0kN/ETfO5ExjNAPyMt2FocO2s/UlCHfjAk=
-github.com/kurin/blazer v0.5.3/go.mod h1:4FCXMUWo9DllR2Do4TtBd377ezyAJ51vB5uTBjt0pGU=
+github.com/kurin/blazer v0.5.4-0.20211030221322-ba894c124ac6 h1:nz7i1au+nDzgExfqW5Zl6q85XNTvYoGnM5DHiQC0yYs=
+github.com/kurin/blazer v0.5.4-0.20211030221322-ba894c124ac6/go.mod h1:4FCXMUWo9DllR2Do4TtBd377ezyAJ51vB5uTBjt0pGU=
 github.com/magiconair/properties v1.8.5/go.mod h1:y3VJvCyxH9uVvJTWEGAELF3aiYNyPKd5NZ3oSwXrF60=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
 github.com/mattn/go-isatty v0.0.3/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=