/tellraw command in clickEvent on a sign doesn't work

setblock ~ ~1 ~ standing_sign 0 replace {Text1:"{color:blue,text:'Test',clickEvent:{action:run_command,value:'tellraw @p {text:"This is the output"}'}}"}

I put this command in a command block.

If I power the command block, nothing happens and the following error message appears, even though the command is correct.

[16:41:58] Data tag parsing failed: Unexpected token 'T' at: This is the output"}'}}"