WebGl: RuntimeError: indirect call signature mismatch

I'm getting this error when running my WebGL build

RuntimeError: indirect call signature mismatch il2cpp::vm::MetadataCache::ExecuteModuleInitializers()@http://localhost:52242/Build/build.wasm.gz:wasm-function[40109]:0x102f1d2 dynCall_v@http://localhost:52242/Build/build.wasm.gz:wasm-function[43755]:0x10d057d invoke_v@http://localhost:52242/Build/build.framework.js.gz:3:411310 main@http://localhost:52242/Build/build.wasm.gz:wasm-function[38301]:0xfc93cc unityFramework/Module._main@http://localhost:52242/Build/build.framework.js.gz:3:336634 callMain@http://localhost:52242/Build/build.framework.js.gz:3:479879 doRun@http://localhost:52242/Build/build.framework.js.gz:3:480434 run@http://localhost:52242/Build/build.framework.js.gz:3:480598 runCaller@http://localhost:52242/Build/build.framework.js.gz:3:479525 removeRunDependency@http://localhost:52242/Build/build.framework.js.gz:3:16011 unityFramework/

I'm not even sure how to begin debugging this. any help would be appricated.