diff --git a/optimum/exporters/onnx/model_configs.py b/optimum/exporters/onnx/model_configs.py
index 78b80138563..fa39a47abfd 100644
--- a/optimum/exporters/onnx/model_configs.py
+++ b/optimum/exporters/onnx/model_configs.py
@@ -147,7 +147,7 @@ def inputs(self) -> Dict[str, Dict[int, str]]:
 
 
 class MPNetOnnxConfig(DistilBertOnnxConfig):
-    DEFAULT_ONNX_OPSET = 12
+    DEFAULT_ONNX_OPSET = 12  # For lower opsets, results in: Type 'tensor(int64)' of input parameter (/0/auto_model/encoder/Add_1_output_0) of operator (Min) in node (/0/auto_model/encoder/Min) is invalid.
 
 
 class RobertaOnnxConfig(DistilBertOnnxConfig):
@@ -817,6 +817,7 @@ def torch_to_onnx_input_map(self) -> Dict[str, str]:
 
 class SentenceTransformersTransformerOnnxConfig(TextEncoderOnnxConfig):
     NORMALIZED_CONFIG_CLASS = NormalizedTextConfig
+    DEFAULT_ONNX_OPSET = 14  # Some bottleneck transformers models require a specific ONNX opset to be successfully exported. We put a rather high opset here for the export to work for all architectures.
 
     @property
     def inputs(self) -> Dict[str, Dict[int, str]]: