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Messages starting with Failed HPSS call: n = ::hpss_Read(fd_,buffer,... are HPSS errors. The actual message text can vary but they usually mean that the data is unavailable from tapes for some time. These errors are passed to the client and make your request fail. As a rule, after checking that there is no ongoing system session, re-run your request before reporting the error. If the failure is consistent, please inform ECMWF's Call Service Desk.
Assertion failed
Error messages starting with Assertion failed: followed by offset[i] > offset[i-1] or handle[n] != 0 hint at an attempt to retrieve the same field more than once, e.g. by specifying param=z/t/z or step=24/48/24. The actual message varies depending on how exactly the data is retrieved. The general advice in such cases is to check the request for multiple occurrences of keyword values.
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