RFC destinations may fail with the error "Failed to open sideinfo.dat" , this wiki provides details on what can cause this error.
This wiki provides details on the error reported in SM59, trace files and the possible solutions.
Identifying the issue
An error similar to the following is reported in SM59:
The corresponding dev_rfc<N> trace will also report the error, for example:
The problem will occur if the RFC destination has not been fully completed.
For example, in SM59, if you are using registeration mode however the ProgramID field is empty. Once the ProgramID details are entered in the destination, the error should no longer occur.
Related SAP Notes/KBAs