diff --git a/third-party/thrift/src/thrift/lib/rust/Cargo.toml b/third-party/thrift/src/thrift/lib/rust/Cargo.toml
index 1e9e619b66252a..3e85328b5b0e73 100644
--- a/third-party/thrift/src/thrift/lib/rust/Cargo.toml
+++ b/third-party/thrift/src/thrift/lib/rust/Cargo.toml
@@ -12,7 +12,7 @@ publish = false
 [dependencies]
 anyhow = "1.0.86"
 async-trait = "0.1.71"
-base64 = "0.13"
+base64 = "0.21"
 bufsize = "1.0.5"
 bytes = { version = "1.6.0", features = ["serde"] }
 futures = { version = "0.3.30", features = ["async-await", "compat"] }
diff --git a/third-party/thrift/src/thrift/lib/rust/any/src/deserialize.rs b/third-party/thrift/src/thrift/lib/rust/any/src/deserialize.rs
index 5ead3ef8819dc9..58f2e4b240e783 100644
--- a/third-party/thrift/src/thrift/lib/rust/any/src/deserialize.rs
+++ b/third-party/thrift/src/thrift/lib/rust/any/src/deserialize.rs
@@ -107,6 +107,11 @@ mod tests {
     use any::Any;
     use anyhow::anyhow;
     use anyhow::Result;
+    use base64::alphabet::STANDARD;
+    use base64::engine::general_purpose::GeneralPurpose;
+    use base64::engine::general_purpose::GeneralPurposeConfig;
+    use base64::engine::DecodePaddingMode;
+    use base64::Engine;
     use standard::StandardProtocol;
     use standard::TypeName;
     use standard::TypeUri;
@@ -116,17 +121,23 @@ mod tests {
     use super::deserialize;
     use crate::AnyError;
 
+    // Bring back the pre 0.20 bevahiour and allow either padded or un-padded base64 strings at decode time.
+    const STANDARD_INDIFFERENT: GeneralPurpose = GeneralPurpose::new(
+        &STANDARD,
+        GeneralPurposeConfig::new().with_decode_padding_mode(DecodePaddingMode::Indifferent),
+    );
+
     fn make_test_any() -> Result<Any> {
         Ok(Any {
             r#type: Type {
                 name: TypeName::structType(TypeUri::typeHashPrefixSha2_256(
-                    base64::decode("e3AbYkUAP8FICiPtbGYI6w").unwrap(),
+                    STANDARD_INDIFFERENT.decode("e3AbYkUAP8FICiPtbGYI6w").unwrap(),
                 )),
                 params: Vec::new(),
                 ..Default::default()
             },
             protocol: Protocol::standard(StandardProtocol::Compact),
-            data: base64::decode(
+            data: STANDARD_INDIFFERENT.decode(
                 "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",
             )?,
             ..Default::default()
diff --git a/third-party/thrift/src/thrift/lib/rust/any/src/thrift_any_type.rs b/third-party/thrift/src/thrift/lib/rust/any/src/thrift_any_type.rs
index 4ee7f689d699c8..1d89beba757115 100644
--- a/third-party/thrift/src/thrift/lib/rust/any/src/thrift_any_type.rs
+++ b/third-party/thrift/src/thrift/lib/rust/any/src/thrift_any_type.rs
@@ -109,6 +109,11 @@ mod tests {
     use any::Any;
     use anyhow::anyhow;
     use anyhow::Result;
+    use base64::alphabet::STANDARD;
+    use base64::engine::general_purpose::GeneralPurpose;
+    use base64::engine::general_purpose::GeneralPurposeConfig;
+    use base64::engine::DecodePaddingMode;
+    use base64::Engine;
     use standard::TypeName;
     use standard::TypeUri;
     use type_::Type;
@@ -118,13 +123,21 @@ mod tests {
     use crate::AnyError;
     use crate::AnyTypeExpectationViolated;
 
+    // Bring back the pre 0.20 bevahiour and allow either padded or un-padded base64 strings at decode time.
+    const STANDARD_INDIFFERENT: GeneralPurpose = GeneralPurpose::new(
+        &STANDARD,
+        GeneralPurposeConfig::new().with_decode_padding_mode(DecodePaddingMode::Indifferent),
+    );
+
     #[test]
     fn test_ensure_thrift_any_type_0() -> Result<()> {
         use artifact_builder_override::ExperimentOverrideRequestContext;
         let val = Any {
             r#type: Type {
                 name: TypeName::structType(TypeUri::typeHashPrefixSha2_256(
-                    base64::decode("e3AbYkUAP8FICiPtbGYI6w").unwrap(),
+                    STANDARD_INDIFFERENT
+                        .decode("e3AbYkUAP8FICiPtbGYI6w")
+                        .unwrap(),
                 )),
                 ..Default::default()
             },
diff --git a/third-party/thrift/src/thrift/lib/rust/src/simplejson_protocol.rs b/third-party/thrift/src/thrift/lib/rust/src/simplejson_protocol.rs
index d71d6ccf1ada3a..c963764149cf5c 100644
--- a/third-party/thrift/src/thrift/lib/rust/src/simplejson_protocol.rs
+++ b/third-party/thrift/src/thrift/lib/rust/src/simplejson_protocol.rs
@@ -20,6 +20,11 @@ use anyhow::anyhow;
 use anyhow::bail;
 use anyhow::Context;
 use anyhow::Result;
+use base64::alphabet::STANDARD;
+use base64::engine::general_purpose::GeneralPurpose;
+use base64::engine::general_purpose::NO_PAD;
+use base64::engine::DecodePaddingMode;
+use base64::Engine;
 use bufsize::SizeCounter;
 use bytes::buf::Writer;
 use bytes::Buf;
@@ -48,6 +53,12 @@ use crate::thrift_protocol::MessageType;
 use crate::thrift_protocol::ProtocolID;
 use crate::ttype::TType;
 
+// Bring back the pre 0.20 bevahiour and allow either padded or un-padded base64 strings at decode time.
+const STANDARD_NO_PAD_INDIFFERENT: GeneralPurpose = GeneralPurpose::new(
+    &STANDARD,
+    NO_PAD.with_decode_padding_mode(DecodePaddingMode::Indifferent),
+);
+
 #[phantom]
 #[derive(Copy, Clone)]
 pub struct SimpleJsonProtocol<F = Bytes>;
@@ -349,10 +360,7 @@ impl<B: BufMutExt> ProtocolWriter for SimpleJsonProtocolSerializer<B> {
             .begin_string(&mut self.buffer)
             .expect("Somehow failed to do \"io\" on a buffer");
         CompactFormatter
-            .write_raw_fragment(
-                &mut self.buffer,
-                &base64::encode_config(value, base64::STANDARD_NO_PAD),
-            )
+            .write_raw_fragment(&mut self.buffer, &STANDARD_NO_PAD_INDIFFERENT.encode(value))
             .expect("Somehow failed to do \"io\" on a buffer");
         CompactFormatter
             .end_string(&mut self.buffer)
@@ -923,7 +931,8 @@ impl<B: Buf> ProtocolReader for SimpleJsonProtocolDeserializer<B> {
                 None => bail!("Expected the string to continue"),
             }
         }
-        let bin = base64::decode_config(&ret, base64::STANDARD_NO_PAD)
+        let bin = STANDARD_NO_PAD_INDIFFERENT
+            .decode(&ret)
             .context("The `binary` data in JSON string does not contain valid base64")?;
         Ok(V::from_vec(bin))
     }