What was reported:
Issue e2b-dev/e2b#1018 (closed, 14 comments): **Describe the bug** I'm using python SDK building custom template with e2b cloud (free tier). It stuck at one step like for an hour: ``` [2025-11-08T07:40:59.120903+00:00] [info] CACHED [builder 46/66] COPY path/to/file /app/path/to/file [...] ``` then error without much information: ``` ... in wait_for_build_finish raise BuildException(build_status.reason or "Build failed") e2b.template.exceptions.BuildException: BuildStatusReason(message='polling received unrecoverable error: rpc error: code = DeadlineExceeded desc = context deadline exceeded', step=<e2b.api.client.types.Unset object at 0x7

What works:
Template builds hang at the file copy step when you use absolute source paths like [HOME]/... or relative up paths like ../../dir. Neither is supported, same as Docker. Use paths relative to the build context with no leading slash and no .. segments and the build proceeds.