Cron - bad minute errors in crontab file, can't install

Question

So I have a cron file sms.cron that I want to execute every 15 minutes that looks like that:

15 * * * * docker-compose exec php bin/console app:send-sms

I do not precise the path to the command cause the command is at root and the sms.cron as well

I try to run it manualy with command :

crontab sms.cron

And get the following error:

"sms.cron":1: bad minute
errors in crontab file, can't install

I get that I have a syntax error but looked at several similar issue on internet and do not see where this error might come from.

Does anyone have any idea on where this syntax error might come from ? Thanks!

UPDATE

Also tried this syntax:

*/15 * * * * docker-compose exec php bin/console app:send-sms

which returned the following error message :

"sms.cron":0: bad minute
errors in crontab file, can't install.

Output of od -c sms.cron:

0000000   `   `   `  \n   *   /   1   5       *       *       *       *
0000020       d   o   c   k   e   r   -   c   o   m   p   o   s   e    
0000040   e   x   e   c       p   h   p       b   i   n   /   c   o   n
0000060   s   o   l   e       a   p   p   :   s   e   n   d   -   s   m
0000100   s  \n   `   `   `
0000105

UPDATE

The issue came from those char: ```

that were present in my cron file before and after my command

Answer 1

I had a similar problem with a file I ported from windows. Did not work until I changed \r\n into \n.
Found it only because of this error message here. Thanks to all!