It is possible to build on the top bedrock layer in the nether, likely due to the height limit being set too high. A good fix would be to lower the building limit in the nether, or move the nether roof up.
MC-309240
You can build on the nether roof after using a glitch with ladders and ender pearls
Resolved
Duplicate
1
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We're tracking this issue in MC-180755, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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