Cancelling a pending Uniswap transaction has a network cost of its own. Uniswap's existing guide describes cancellation as submitting an empty transaction with a higher network fee.
Before choosing that route, search your wallet address on the relevant block explorer and check whether the original transaction was broadcast and is still pending. Waiting is another option; the guide says cancellation may be possible, not that it is guaranteed.
If the explorer shows several pending transactions, Uniswap directs users to support rather than giving the same cancellation instructions.
Source: https://support.uniswap.org/hc/en-us/articles/7422909292813-My-transaction-has-been-pending-for-a-long-time-What-can-I-do
Before choosing that route, search your wallet address on the relevant block explorer and check whether the original transaction was broadcast and is still pending. Waiting is another option; the guide says cancellation may be possible, not that it is guaranteed.
If the explorer shows several pending transactions, Uniswap directs users to support rather than giving the same cancellation instructions.
Source: https://support.uniswap.org/hc/en-us/articles/7422909292813-My-transaction-has-been-pending-for-a-long-time-What-can-I-do