When wallet signature fails, you still have several alternative methods to prove ownership. The most common are the Satoshi Test (micro transaction), fallback options like screenshots/screen recording, and AOPP (Address Ownership Proof Protocol) which automates the signature process.
Method 1: Satoshi Test (Micro Transaction Verification)
If the exchange shows a signature error, it usually offers a second option: send a tiny specific amount (usually a few hundred to a few thousand satoshis) to a designated address. Once the exchange sees the on-chain transaction, it confirms you have the private key for that address.
Step 1: Get the exchange's test instructions
On the verification page, find the "Micro Transaction" or "Satoshi Test" option and copy the target address and exact amount provided. Make sure the amount matches perfectly — one extra or missing zero will cause failure. Complete when you have the target address and precise amount.
Step 2: Send the test transaction from your target wallet
Using the wallet you need to verify, send the specified amount to the exchange's address. Note: you need extra for gas fees; the required amount does not include gas. If your wallet balance exactly equals the test amount, you must first deposit some extra to cover gas, then send the test transaction. Complete when the transaction is confirmed on-chain (usually one block confirmation is enough, but check the exchange's requirement).
Risk note: Funds sent in the Satoshi Test are deducted from your wallet. Some exchanges refund them, some don't. Before sending, check the amount and network fees to avoid high costs. For ERC-20 token tests, you may also need ETH as gas.
Method 2: Screenshots / Screen Recording (Visual Proof)
Some wallets don't support message signing, and some platforms allow verification through screenshots or video. This method doesn't rely on wallet signing features and works with all wallets. The downside is manual review, and in some regions it's no longer accepted — because screenshots can be easily manipulated with AI.
Step 1: Record the full process
Film a video showing the address you need to verify inside the wallet app. You must use a separate device to record — screen capture is not accepted. Complete when the video clearly shows the address, wallet balance, and current interface, with the wallet app visibly running (not a static page).
Step 2: Submit for manual review
Upload the screenshot or video to the verification page and wait for review. The review may take a few minutes to several hours, depending on the exchange's queue. Complete when the status changes to "Verified" or "Approved".
Method 3: AOPP Link Automated Verification
If the exchange supports AOPP (Address Ownership Proof Protocol), this is a simpler alternative to manual signing. It's essentially an automated version of signature verification: the exchange generates a link, you open it and confirm with your wallet, and the system completes the signing and verification in seconds. Countries like Switzerland now explicitly require "suitable technical means" to verify wallet ownership, with AOPP being one recommended solution.
Common reasons for failure
The most common reason for verification failure is a message format mismatch when signing manually — the exchange's message contains specific text, timestamps, or user IDs, and even an extra space can invalidate the signature. Another reason is that the wallet doesn't support message signing (some mobile wallets for BTC/SOL addresses lack this feature). You can switch to a web wallet to complete the process.
Next steps
First, check if the exchange's verification page offers an "alternative verification method" — usually screenshots/video are fallbacks, while the Satoshi Test or AOPP are primary choices. If signing keeps failing, go straight for the Satoshi Test or screenshot upload to avoid wasting time. After submission, save the transaction hash (TxID) so you can track progress with customer support.
