I'm a non EU citizen. Currently I have a German Blue Card residence permit. I'm planning to apply for a permanent residence (after 21 months with B1 German Knowledge proof). The problem now is that I'm starting a new job and things got unexpectedly interrupted. Because of this I may be 2 weeks without an employer/job. I'm wondering whether this will affect my plans of asking for the permanent residence as I will have a small gap without pension contributions. Has anyone been in a similar situation? Do you know if there is something in the law that states the required full continuity of the contributions before asking for the permanent residence?
No direct experience with this situation but reading the relevant part of the law, I see nothing suggesting the contributions must be continuous. In fact, the contribution requirement defined in § 18c Abs. 1 Nr. 3 is separate from the requirement to hold a residence permit for 4 years defined in Abs. 1 Nr. 1., which is explicitely continuous (and which doesn't directly apply to you).
Furthermore, the requirement is to have contributed for 21 months, not for every single day of 21 months (which doesn't really make sense anyway). If you are only two weeks without a job, you would presumably still pay something in the relevant month(s) based on the time worked on either side of the employment gap. If that's the case, it seems you wouldn't have to wait a minute longer or worry about interruptions as you would in fact be able to document a continuous period of 21 months when you contributed to the statutory pension system.