While using gRPC at work we started to notice PHP throwing the following error when attempting to communicate via the gRPC extension: *Maximum call stack size of 10436608 bytes (zend.max_allowed_stack_size - zend.reserved_stack_size) reached. Infinite recursion?*

My initial investigation uncovered [issue 39509 raised against `grpc/grpc` on Github](https://github.com/grpc/grpc/issues/39509) which confirmed the same problem I was seeing was more widespread and related to something internal to the gRPC extension that was introduced in v1.67.0.

For the time being I have downgraded us to v1.66.0 of gRPC.

- https://github.com/grpc/grpc/commit/245941e0da74afa3e5446105ca3baad2f3bd8a70
- https://github.com/grpc/grpc/compare/v1.66.0...v1.67.0#diff-b468864be3a47863ed0cb9dcf59ce107929f46e5789fff9a5cab33043eeb5518
- https://github.com/grpc/grpc/issues/38184
- https://github.com/grpc/grpc/issues/39509