This post is for informational purposes only, please review the manufacturer documentation for any product before purchasing and verify that it is suitable for your application.
ECWU4103V17 is an obsolete film capacitor from Panasonic Industry.
The best option I found in stock was part number 478-10945-1-ND (CB037G0103JBA), produced by KYOCERA AVX. It is not a perfect cross-reference, but it it the best option I could find with similar size, capacitance, and voltage ratings. The DC voltage rating is lower than the original part so please keep that in mind.