The mexc-exchange-api package vendors a copy of CCXT under:

mexc/ccxt/

However, the vendored CCXT does not include the protobuf directory, while the code imports it explicitly.

Example import used inside the package:

from ccxt.protobuf.mexc import PushDataV3ApiWrapper_pb2

When this code runs in the context of the mexc package, ccxt resolves to mexc.ccxt, and the import fails because mexc/ccxt/protobuf is missing.

Manually copying the protobuf directory from the official ccxt package resolves the issue:

site-packages/ccxt/protobuf
→ site-packages/mexc/ccxt/protobuf

After this, MexcWs and other WS functionality work correctly.