Solomon elected free agency Thursday.
Solomon cleared waivers and was outrighted to Triple-A Reno on Thursday.
Arizona designated Solomon for assignment Monday.
The Diamondbacks optioned Solomon to Triple-A Reno following Tuesday's 6-4 loss to the Rangers.
The Diamondbacks selected Solomon's contract from Triple-A Reno on Saturday.
Solomon was reassigned to minor-league camp by the Diamondbacks on Sunday.
Solomon allowed one hit and two walks while striking out two over 2.2 scoreless innings in Saturday's spring start against the Mariners.
Solomon cleared waivers and was outrighted to Triple-A Indianapolis on Thursday, Rob Biertempfel of The Athletic reports.
The Pirates claimed Solomon off waivers from the Astros on Sunday and optioned him to Triple-A Indianapolis, Justice delos Santos of MLB.com reports.
Solomon was designated for assignment by the Astros on Thursday.