I guess Google wanted to start with a clean slate based on the design principles already established internally (a system called Stubby).

gRPC was designed from the start for HTTP/2, which comes with some benefits: It's able to work wherever HTTP works (load balancers and proxies), can multiplex calls over a single stream (Thrift on the JVM, where it's most popular, uses a thread per socket), supports cancelation and streaming and so on. gRPC is arguably more opinionated than Thrift here; Thrift is both a serialization format and an RPC mechanism, and for Thrift RPC you can choose between different transports and framings, of which HTTP is just one. gRPC is HTTP-only, and is (at least nominally) serialization-format-agnostic; you could, in principle, use Thrift over gRPC instead of Protocol Buffers, for example. So in this sense, gRPC is more pure and generic than Thrift. (I'm sure Thrift fans might disagree here.)

I haven't actually used Thrift, so maybe someone else can chime in about other reasons gRPC is preferable.

My understanding is that Thrift is Facebook's analog to Google's Stubby. Or gRPC [which is the next generation of Stubby].

It's not implementing the gRPC interface. I don't think gRPC was open-sourced [2015] early enough for Thrift [2007] to be built to its API.

Disclosure: Google employee who uses Stubby. [but is not on the team]

Thrift was written at Facebook by an ex Google intern trying to recreate something close to protobuf+Stubby.

Thrift is comparable to GRPC, and more user-friendly in practice than GRPC. GRPC is more flexible, rigorous (anal).

I disagree that Thrift failed, but GRPC has more momentum right now IMO.

Source (GRPC at current startup, multiple years of thrift)

Thrift is popular and it "supports" more targets, but I found a lot of bugs in some of its lesser-known implementations. This may not be an issue if you're using a widely-used Thrift platform, but if you're choosing Thrift because it supports the target you want while another RPC doesn't, do watch out for weird bugs and issues.

I haven't tried to use Protobufs or gRPC in a serious way so I can't say if it's better or worse, but I would hope it supports fewer targets because it takes stability and QC more seriously.

on the contrary, I always found thrift lack good documentation.

That's the sense I got too but beyond the initial hurdles it's good enough.