1# gRPC Server Backward Compatibility Issues and Workarounds Management
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3## Introduction
4This document lists the workarounds implemented on gRPC servers for record and reference when users need to enable a certain workaround.
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6## Workaround List
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8### Cronet Compression
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10**Workaround ID:** WORKAROUND\_ID\_CRONET\_COMPRESSION
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12**Date added:** May 06, 2017
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14**Status:** Implemented in C core and C++
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16**Issue:** Before version v1.3.0-dev, gRPC iOS client's Cronet transport did not implement compression. However the clients still claim to support compression. As a result, a client fails to parse received message when the message is compressed.
17The problem above was resolved in gRPC v1.3.0-dev. For backward compatibility, a server must forcingly disable compression for gRPC clients of version lower than or equal to v1.3.0-dev.
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19**Workaround Description:** Implemented as a server channel filter in C core.  The filter identifies the version of peer client with incoming `user-agent` header of each call. If the client's gRPC version is lower that or equal to v1.3.x, a flag GRPC_WRITE_NO_COMPRESS is marked for all send_message ops which prevents compression of the messages to be sent out.
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