PROBLEM DESCRIPTION or QUESTION
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I have a User key without passphrase, when I import key Remind me input passphrase, I not have input everything, hit enter key. Prompt error:" Failed to import the user key:
Invalid user key file or incorrect passphrase."
RESOLUTION
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Your key also cannot be read with OpenSSH keys tools and other terminal emulators. So we inspected your key and found that the key has been modified. We believe the reason may be related to the CR-LF issue of ASCII file transfers via the FTP protocol. We've attached a file in which the CR-LF issue has been fixed.
Please try the import key test again with the attached file. I recommend you DO NOT use this file in your real server. Create a new one from the cloud.